New report explores implications of tests to estimate timing of HIV infection for criminal prosecutions

From UNAIDS front page today.


Feature Story: New report explores implications of tests to estimate timing of HIV infection for criminal prosecutions

The UK charity National AIDS Trust (NAT) launched a report on 4 August 2011, entitled Estimating the likelihood of recent HIV infection – implications for criminal prosecution, which explores the validity and meaning of the Recent Infection Testing Algorithm HIV tests, or RITA tests, within the context of criminal prosecutions of HIV transmission.

The report, primarily aimed at professionals working in the criminal justice system and HIV specialists who may be called on as expert witnesses in criminal HIV transmission cases, calls for caution about the potential use of RITA results to determine timing of HIV infection.

About RITA and its potential use in criminal law context

RITA tests estimate the likelihood that a person found to be HIV-positive has been infected recently, usually within the previous six months. To date, the United Kingdom is the only country reported to routinely return RITA results to newly diagnosed patients.

As criminal law in the UK allows for the prosecution of people for transmitting HIV to another person, the report underlines the importance that RITA tests and their limitations be fully understood and not misused in criminal proceedings. The report underlines that while there have been no reported instances of use of RITA results in courts to attempt to prove timing of HIV transmission and consequently the identity of the person who transmitted HIV, this may happen in the near future.

No test can conclusively state when an individual acquired HIV

“No scientific test is able to conclusively state when an individual acquired HIV,” said Dr Cate Hankins, Chief Scientific Adviser to UNAIDS. “It is important to be cautious, follow clear protocol, and understand the limitations of RITA results when delivering them to patients or using them within a criminal law context.”

According to the report, proving HIV transmission in the context of criminal law cases requires the use of a combination of scientific evidence, medical records and testimony to establish the facts, timing and direction of HIV transmission.

“Scientific advances such as RITA testing are extremely welcome when estimating the recency of HIV infection on a population level, especially as late diagnosis is a huge issue,” said Ms Deborah Jack, Chief Executive of National AIDS Trust. “However, it is crucial that the limitations of RITA tests are fully understood and are not used out of context, for example during criminal proceedings.”

As RITA tests are designed to work at the population level (based on averages) rather than at the individual level, taking into account significant rates of false RITA test results in individuals, the report draws the conclusion that RITA tests are not reliable as evidence of recent HIV infection for individuals in the context of criminal proceedings.

Better understanding of HIV science in the context of criminal law

The NAT report comes weeks ahead of an expert meeting on the scientific, medical, legal and human rights aspects of the criminalization of HIV transmission and exposure organized by UNAIDS in Geneva from 31 August to 2 September 2011.

The meeting will bring together leading scientists and medical experts on HIV together with legal and human rights experts. Participants will examine relevant scientific and legal evidence and concepts relating, among others, to harm, risk, intent and proof, and their conceptualization/application in the context of criminalization of HIV exposure and transmission.

The meeting is part of UNAIDS’ work towards halving the number of countries with punitive laws and practices around HIV transmission, sex work, drug use, or homosexuality that block effective AIDS responses by 2015.

New Zealand: Charges dropped in criminal HIV transmission case

All charges against a Wellington man accused of not disclosing his HIV-positive status prior to unprotected sex with his female partner who subsequently tested HIV-positive have been dropped because police are unable to trace the complainant.

Not only did Justice Simon France drop the charges of “wounding with intent to cause grievous bodily harm” but also ordered that the man’s name be suppressed.

Jo Murdoch, a lawyer from the Public Defence Service, successfully argued in court that the man’s identifying particulars should be suppressed.

Justice Simon France said the issue became whether the man’s HIV status – a particularly private and sensitive medical fact – should be exposed when grave doubts had been raised about the alleged victim’s credibility.

The case did not have the public interest element of a person accused of having put multiple partners at risk or having risky casual sex. Also, the alleged crime was irrelevant to his employment and his contact with the public generally. Taken together the circumstances outweighed the usual principle that justice should be carried out publicly, Justice France said.

Details of the case are sketchy and come from a single story in today’s Dominion Post via

(Pdf of webpage here if link no longer works.)

Police said he did not tell his partner he had HIV, the couple had unprotected sex and she contracted the disease. The man said his partner of several years knew of his condition and that they always had protected sex.

Shortly before the trial was due, information came to light which, if true, would have affected a court’s view of her honesty. Police were unable to find her and thought she was hiding from them. They had wanted to check the information before expensive tests to see if the couple had the same strain of HIV.

The Crown offered no evidence against the man, resulting in a discharge which amounted to an acquittal.

Evidence: Claims that phylogenetic analysis can prove direction of transmission are unfounded, say experts

I’m reproducing this news article I wrote for in case anyone hasn’t seen it, because it is a really important issue.  Claiming that phylogenetic analysis is so reliable as to be able to ‘prove’ who infected who in a criminal court case is reckless and somewhat self-serving.

A report from the United States published last week in the Proceedings of the National Academy of Sciences claims to show for the first time that direction of HIV transmission from one individual to another for use as evidence in criminal trials can reliably be established by phylogenetic analysis. However, international experts in phylogenetics who have acted as forensic advisors in criminal courts tell that the report “draws unwarranted conclusions”.

The report, co-authored by Michael Metzker, associate professor at the Baylor College of Medicine Human Genome Sequencing Center and David Hillis, a professor of evolutionary biology at the University of Texas, details the phylogenetic analysis methodology used in two criminal HIV transmission cases in the United States, in Washington State in 2004 and Texas in 2009, respectively.

These cases were only the second and third times that phylogenetic analysis was used as evidence in a criminal prosecution in the United States, despite at least 350 convictions under HIV-specific and/or general criminal laws for HIV non-disclosure, alleged exposure and/or transmission since prosecutions began in the mid-1980s (CHLP, 2010). Of note, both of these cases involved allegations of multiple heterosexual transmissions from a single source. Such allegations are extremely rare in criminal cases.

Phylogenetic analysis requires the use of complex computational tools to create a hypothetical diagram (known as a phylogenetic tree) that estimates how closely related the samples of HIV taken from the complainant(s) and defendant are likely to be in comparison to other samples.

The report refers to several recent studies (including a 2008 study from Keele and colleagues) which suggest to the authors that a “significant genetic bottleneck” may occur during HIV transmission, and that at least three-quarters of infections may result from a single virus. It also notes that since HIV evolves rapidly following initial infection, this results in “increased diversity of HIV sequences within a newly infected individual.”

However, the report argues that if blood samples are taken from the accused and complainant(s) “shortly after a transmission event” the population of viral sequences in one individual would be expected to be more closely related to the population in the other(s) than other populations of viral sequences used for comparison. This is known as a “paraphyletic relationship.” The paper then suggests that “paraphyly provides support for the direction of transmission and, in a criminal case, could be used to identify the index case (i.e., source).”

In both cases, the investigators were blinded as to the identity of the accused and the complainants, which was only revealed in court once they had provided their report to the prosecution. Again, in both cases, the sample they identified as being the source of infection was that of the accused. It is unknown how much weight the judge and jury gave to the phylogenetic reports, but it is known that the prosecution provided a great deal of supporting evidence – including, in the Texas case, contact tracing and HIV testing of most of the complainants’ prior sexual partners – and that it was the totality of such evidence that led to guilty verdicts and lengthy prison sentences in both cases.

The paper and its assertions have been widely disseminated via a press release and several articles primarily aimed at the scientific community. Such articles include quotes from the investigators that suggest their methods are unquestionably sound and it was this evidence alone that led to the guilty verdicts. “This is the first case study to establish the direction of transmission,” Professor Metzker was quoted in an AFP story with the headline ‘ Lab detectives use science to nab HIV criminals’.

He asserted to the American Statesman that “[our analysis] provided sound scientific evidence of the direction of transmission, and from that we could identify the source.”  The article also quotes the main prosecutor in the Texas case, who characterises phylogenetic analysis as “good evidence”.  Of note, the defence attorney in the case is quoted as saying they were unable to find an expert to testify in court against the reliability of Hillis and Metzker’s findings.

“It made a lot of difference in trying the case because we couldn’t find an expert for our side,” he said.

However, Professor Metzker’s claims and the paper’s assertion that he and his colleagues have established that their methodology is both a new and reliable method of proving the direction of transmission has been questioned by several international experts contacted by All of the experts have served as witnesses in criminal trials outside of the United States.

These experts all agree that phylogenetic analysis remains an informed but sometimes imperfect estimate of the relationship between viruses. Although there are a variety of methods by which it is possible to increase the confidence that the samples are very closely related in comparison to other samples, there could never be complete confidence that the defendant infected the complainant(s) based on phylogenetic analysis alone.

Anne-Mieke Vandamme, a professor at Leuven Catholic University and Rega Institute in Belgium, has serious reservations regarding the paper’s assertions. “This paper draws unwarranted conclusions,” she tells “There is still the possibility that there is a missing link, a consecutive transmission with an intermediate missing link. I would only use such paraphyletic clustering to exclude a direction of transmission. The elimination of all other possible contacts is something to be done outside the phylogenetic analysis.”

Jan Albert, a professor at the Karolinska Institute and Karolinska University Hospital in Sweden, tells that “the study suggests, but does not prove, transmission between the examined persons. The main reason for the caveat is that the analyses do not exclude the existence of unsampled persons belonging to the same clusters. The paraphyly does not exclude this possibility. In light of this it is surprising that only 20 local controls were investigated in the Washington case and none in the Texas case.”

Thomas Leitner, staff scientist at Los Alamos National Laboratory in the United States, tells that the methodology described in the paper to test the hypothesis of direction of transmission is not, in fact, new, and that along with co-author Walter Fitch he published a paper outlining a similar methodology eleven years ago. (Leitner T, Fitch WM 1999) He adds that his research suggests that even when all persons involved in an alleged transmission chain are sampled, it may still be the case that the two closest samples in a phylogenetic tree are two individuals who may not have ever met.

Professor Vandamme is also lead author of a paper currently in press with The Lancet Infectious Diseases along with several authors including Professor Albert and Dr Anna Maria Geretti, of University College London Medical School, Royal Free Hospital, in London, which highlights the substantial risk of miscarriages of justice based on a flawed view of the science behind phylogenetic analysis. It concludes, in concurrence with a briefing paper co-authored by Professor Vandamme and Dr Geretti and published by NAM and NAT in 2007, that the only ‘safe’ use of phylogenetic analysis in criminal HIV transmission cases is to exonerate the accused.

A fuller discussion of how phylogenetic analysis and other evidence can – and cannot – be used to establish the fact of transmission from the accused to  complainant(s) in a criminal case can be found in the ‘Proof’ chapter of NAM’s new international resource, HIV and the criminal law.


Scaduto DI et al. Source identification in two criminal cases using phylogenetic analysis of HIV-1 DNA sequences. Proceedings of the National Academy of Sciences, published online before print November 15, 2010, doi: 10.1073/pnas.1015673107, 2010.

Abecasis AB et al. Science in court: the myth of HIV ‘fingerprinting’. Lancet Infectious Diseases, 2010 (In Press).

Center for HIV Law and Policy (CHLP) Ending and Defending Against HIV Criminalization: State and Federal Laws and Prosecutions, Vol.1, CHLP’s Positive Justice Project, First Edition, Fall 2010.

Leitner T, Fitch WM The phylogenetics of known transmission histories. Pp. 315-345 in K. A. Crandall. Molecular Evolution of HIV. Johns Hopkins, Baltimore, MD 1999.

UK: HIV transmission case dropped against gay Doncaster man

A case against a gay man in Doncaster, in the north of England, who was accused of ‘recklessly’ transmitting HIV to two male complainants, has been dropped due to lack of evidence – apparently there had been no investigation of the previous sexual partners of the complainants who may have infected them.

I don’t have a lot of details about the case, which I first heard about in March 2009, and I would like to protect the identity of the accused who has obviously been through hell for at least 15 months.

What I do know is this: two men had complained to the police that they believed that they had been infected by the accused during separate dates. (I don’t know whether the complainants knew about each other before they went to the police, or after).

The Crown Prosecution Service (CPS) took their complainants seriously enough to prepare a ‘reckless grievous bodily harm’ prosecution under Section 20 of the Offences Against the Person Act 1861. To prove the element of causation of such ‘grievious bodily harm’ (i.e. HIV transmission), the prosecution must prove beyond reasonable doubt that only the accused could have infected the complainant(s).

I’m reliably informed by the man’s defence lawyer, Khurram Arif, that the trial was meant to commence yesterday at Doncaster Crown Court. The defence had prepared a scientific report examining the likelihood that only the accused could have infected both complainants. The report highlighted that the complainants’ previous sexual partners may also have infected them and that phylogenetic analysis could not rule this out.

Yesterday, the prosecution consulted with its own scientific expert and conceded that since both complainants had previous sexual partners and the police did not investigate nor eliminate them as possible sources of infection, there was no case to answer. This is, in fact, what the CPS guidelines state.

This is one of several cases defended by Mr Arif, where a lack of attention to the detail of what scientific evidence can – and cannot – prove has led to the CPS dropping cases very late in the day. As Mr Arif notes in his email to me: “The prosecution, when making such allegations, have to prove that they have closed all the doors to the possible sources of infection. Again, in this case, they did not.”

The case highlights that in England & Wales, people accused of such ‘crimes’ should never plead guilty and should immediately contact an HIV organisation for advice in order to be put in touch with an expert defence lawywer, such as Mr Arif, who services legal aid clients through Christian Khan Solicitors and private clients through GSC Solicitors.

In addition, complainants need to be aware that making such accusations requires them to reveal their entire previous sexual history and to name all of their sexual partners since their last HIV-negative test. Only when they have all been contacted and tested for HIV can a prosecution actually reach trial.

US: Padieu case gets the 20/20 treatment; phylogenetic analysis totally misrepresented

The case of Philippe Padieu, the French-born Texan found guilty in May 2009 on six counts of aggravated assault with a deadly weapon and sentenced to 45 years for five counts and 25 years for the remaining count – all of which run concurrently – was featured last Friday night on US ABC TV’s tabloid-style news magazine, 20/20.

Five and half million viewers watched as Mr Padieu faced trial by media yet again. All six parts of the one hour show (actually 39 minutes minus commercials) are available to watch online.

Part 1: Women recall HIV criminal’s allure
Part 2: HIV diagnosis rocks women’s lives
Part 3: Women take matters into own hands
Part 4: HIV serial dater faces victims in court
Part 5: Man convicted of HIV crime speaks
Part 6: Women want case known to protect others

It’s basically sold as the story of a group of scorned women uniting to put Mr Padieu behind bars, summarised beautifully by the accompanying story on the ABC news website headlined, ‘How Women United to Stop HIV-Positive Man, Women’s Horror at Diagnosis Replaced With Mission: Stop Man From Infecting Others.’

There’s so much I could say about the show, which is something of a milestone in criminal HIV transmission reporting in the mainstream media, but I’m going to limit my comments about the very worrying misrepresentation of phylogenetic analysis as ‘proof’ that Mr Padieu was the source of all the women’s HIV infection. Perhaps blog readers could fill in the comments sections with insights and criticisms of their own about this programme.

[Update: Catherine Hanssens of The Center for HIV Law and Policy has some terrific comments and insights in her Sept 29th blog post.]

In Part 4 of the show, presenter/journalist Elizbeth Vargas says that it was Mr Padieu’s “own DNA” that proved he was guilty. But phylogenetic analysis is all about testing the genetics of HIV, not the individual. They then showed one of the US’s foremost experts in HIV forensics, Dr Michael L Metzker, of Baylor College of Medicine, Houston, Texas, who testified for the prosecution that Mr Padieu’s virus was extremely similar to that of the six women. Except here he says definitively that Mr Padieu was “the source” of the six women’s HIV. I’ve written about the limitations of phylogenetic analysis many times: the issues are summarised here.

In the final part of the show, we are introduced to ‘Lisa’ who dated Mr Padieu in 1997, and was diagnosed HIV-positive that same year. The show gives Dr Metzker a sample of Lisa’s blood and he says that “preliminary analysis” suggests that Mr Padieu was the source of all seven women’s HIV infection. The show concludes that Mr Padieu “gave Lisa HIV in 1997” and goes on to suggest, without a shred of evidence, that he had been diagnosed earlier than 2005 and knowingly infected Lisa and possibly hundreds of other women.

I’m extremely disappointed in Dr Metzker for totally misrepresenting what phlyogenetic analysis can prove. It is impossible to conclude, given the many limitations of phylogenetic analysis, that Mr Padieu infected Lisa in 1997. It is, in fact, just as possible that Lisa infected Mr Padieu.

I don’t expect 20/20 to explain the science (in fact, I expect them to get it wrong), but I do expect Dr Metzker, who is (was?) considered to be a respected scientist, to be less definitive about his conclusions. Maybe Dr Metzker would like to explain how he could be so sure – it would be very helpful to know if he has developed new, as yet unknown, techniques in phylogenetic analysis that can definitively pinpoint timing and direction of transmission.

US: Texan man found guilty of aggravated assault with a deadly weapon for reckless HIV transmission

A Texas jury has found 53 year-old Philippe Padieu of Frisco, Texas, guilty of six counts of aggravated assault with a deadly weapon. He is the sixteenth person with HIV in Texas to be successfully prosecuted for either HIV exposure or transmission since 1997.

Update: May 30th.

Original posting, from May 28th, below:

Mr Padieu was arrested in July 2007 after two women went to police after testing HIV-positive . The police investigation led to four further complainants.

The case has had widespread media coverage throughout the United States, highlighted in today’s Dallas Morning News story summarising the trial.

After five hours of deliberations, the [jury’s] guilty verdicts were read in a large ceremonial courtroom where the trial was moved to accommodate local and national TV crews covering the case, including ABC’s 20/20.

Prosecutors likened Mr Padieu to a “ticking time bomb, a lethal weapon.”

“It’s as if he took a gun and shot all of them,” prosecutor Lisa King said during closing arguments earlier in the day. “But a gunshot wound heals. In this case, he gave them a virus that causes a disease that may well kill them.”

[Assistant District Attorney Curtis] Howard said, Padieu is “a ticking time bomb, he’s a lethal weapon,” and he likened Padieu to Typhoid Mary. He told jurors that Padieu broke the law by knowingly, recklessly and intentionally having sex with multiple women, exposing them to HIV, the virus that causes AIDS, without telling them.

His defence attorny, Bennie House, argued that Mr Padieu was in denial and that the six female complainants should have protected themselves knowing that unprotected sex can result in the transmission of sexually transmitted infections.

“They asked Mr. Padieu if he was safe, he said yes,” said House. “He’s in denial.” He added, “Mr. Padieu is not a predator. … He likes sex…House said his client’s partners had a responsibility to practice safe sex. “They should have invoked a mantra – no glove, no love,” House said. “If that didn’t happen, they should walk out.”

Another of Mr Padieu’s defence lawyer, George A. Giles, argued – rather unsuccessfully given the many previous Texan convictions for HIV-positive bodily fluids being classed as deadly weapons, including Willy Campbell, who was sentenced to 35 years for spitting at a cop – that Texan law did not specifically say that his client had committed aggravated assault.

[He said that] what Padieu did does not constitute aggravated assault. He suggested that prosecutors go to Austin to lobby for changes in the law if they want to use the criminal code to address the practice of unsafe sex by someone with HIV. “When does he have to tell them or anybody he’s got a disease?” Giles said.

However, since the law in Texas is not HIV-specific, the bar was set much higher for the prosecution to prove that Mr Padieu actually infected the six women. They used one of the US’s foremost experts in HIV forensics, Dr Michael L Metzker, of Baylor College of Medicine, Houston, Texas, to testify that Mr Padieu’s virus was extremely similar to that of the six women, although he came to a conclusion that may not have been totally scientific.

The news website of NBC Dallas Fort/Worth reported:

He said he used a national database of HIV positive blood samples and compared the samples taken from Padieu and his six alleged victims. In what was called a blind study, Metzker never knew who each sample belonged to.

“I wanted anonymous samples,” he said. “I did not want to know the identity of any of the individuals, we treated them all equally, generated the data, generated the alignments.”

Metzker said Padieu is the source of his accusers’ infection.

“One sample stood out as the potential source of most, if not all, of the other samples,” he explained.

However, Padieu’s attorneys got Metzker to admit that the study reaches a conclusion, but cannot be called an absolute fact.

The defense is focusing on the fact that HIV can mutate and change over time.

Mr Padieu will be sentenced tomorrow (Friday May 29th). He faces sentencing that ranges from five to 99 years in prison on each of the six counts.

UK: Gonorrhoea prosecution ‘a dangerous development’

I am posting an excellent analysis by Dr Matthew Weait, Senior Lecturer in Law and Legal Studies at Birkbeck College, London (and author of Intimacy and Responsibility: The Criminalisation of HIV Transmission) of the recent successful prosecution of a male migrant for ‘recklessly’ transmitting the sexually transmitted infection, gonorrhoea, through non-sexual means.

A Dangerous Development
by Dr Matthew Weait
Senior Lecturer in Law and Legal Studies
Faculty of Lifelong Learning
Birkbeck College, London

In the recent case of R v Peace Marangwanda [2009] EWCA Crim 60, the English Court of Appeal was called upon to hear an appeal against sentence that has potentially profound implications for debates surrounding the criminalisation of HIV and other serious sexually transmissible infections. Summarised, the facts were that the applicant (PM) had been charged with two offences of sexual activity with a child, contrary to section 9(1) and (2) of the Sexual Offences Act 2003. It had been alleged that PM had met the mother of the children (E and Z), started a relationship and moved in with her in September 2005. In November 2005 PM was diagnosed with gonorrhoea, and he received treatment. A month later, in December 2005, the children, E and Z, were diagnosed as having contracted gonorrhoea. PM was charged, prosecuted and tried in 2007 after E made a complaint fo sexual abuse. The jury could not agree on a verdict after hearing PM’s defence that he was not suffering from gonorrhoea at the relevant time, and that it was rather a severe from of thrush. A retrial was scheduled to take place in June 2007. Prior to the retrial a compromise was suggested by defence counsel whereby PM would plead guilty to two counts of recklessly inflicting grievous bodily harm contrary to section 20 of the Offences Against the Person Act 1861. on the basis that he had recklessly transmitted gonorrhoea to E and Z.

The plea was entered

“ … on the basis that the Defendant, whilst possessed of the knowledge that he was suffering from gonorrhoea, recklessly passed on the said gonorrhoea to the two complainants.

2. Such transmission was carried our not in any way by means of any sexual contact, direct or indirect. Such transmission was likely to have been occasioned in circumstances where the Defendant, after having touched himself and then failing to apply the proper hygiene standards, has then gone on to touch the children in an ordinary way. The Defendant would, on occasion, be involved in the daily care of the two young Complainants. This would include assisting with washing, dressing and general supervisory activities with the same.

3. It was foreseeable that such a condition as gonorrhoea could have been passed and accordingly the Defendant failed in ensuring that he adhered to the proper sanitary and hygienic principles which would have been ordinarily implied.”

PM was sentenced to two years immediate imprisonment on each count, to be served concurrently. He was also recommended for deportation, disqualified from working with children for life and made subject of a Sexual Offences Prevention Order.

PM appealed on a number of grounds, one of which was that he had pleaded guilty to offences that were not medically possible and another that, even if it were medically possible, he had not acted recklessly. (The two other grounds are not of such immediate relevance here and are not discussed – see the case report.) The Court of Appeal agreed that the sentence passed was manifestly excessive and that a sentence of 12 months on each count should have been passed, to be served concurrently. For legal reasons this meant that the order relating to not being able to work with children was quashed, but the other orders were upheld.


This is an important and worrying decision for a number of reasons. The plea of guilty to the charges under section 20 were entered on the understanding that the gonorrhoea had been passed through casual touching. PM, it was accepted, cared for E and Z (which included physical touching). The pre-sentence report (which is prepared to assist the judge in sentencing) stated that

“The defendant has pleaded guilty to the offence in accordance with the basis of plea, namely that he inadvertently passed on gonorrhoea to the two children due to poor personal hygiene.

Mr Marangwanda was, at the time of the offence, in a relationship with the mother of the two victims. He was periodically living at the family home and as such will have regular conduct with the children.

The defendant accepts culpability in as much as he acknowledges he passed on the sexually transmitted infection to the two girls due to poor personal hygiene.

The defendant accepts that his behaviour was reckless and that as a result, two young children contracted a sexually transmitted infection.”

It was on this basis that PM was sentenced, and the Court of Appeal accepted the reasoning. It states (at paragraph 12) that

In the judgment of this court, by his plea, the defendant accepted the medical possibility of the transmission of that disease. As he knew he had gonorrhoea, provided he knew that that disease may be transmitted by transference of mucosa by hand, that transference would have constituted a reckless act …

The Court goes on to say (at para 13) that

… by virtue of the basis of plea and the applicant’s pleas, he must have been accepting the possibility that in a domestic or familial setting the disease could have been transferred. In such circumstances it would have been his duty to take the necessary protection to ensure there was no transference. We are not persuaded that there is anything in that ground of appeal.

This is, it is suggested, deeply problematic, as are other aspects of the case. First, the Court seems to be suggesting that there is a duty to take the necessary protection against the transmission of disease. With respect, there exists no such legal duty anywhere in English law. A person is not reckless because he fails to take precautions against transmission; he is reckless if it is established that he was aware of the risk of transmission. This might seem a fine distinction , but it is an important one. If the Court is thinking particularly of the positive obligation that a carer has towards children, then it should have articulated that far more clearly. In the absence of clarification it suggests that a person living with HIV has a positive obligation – enforceable at law – to prevent onward transmission to sexual partners. (And, in the light of the recent Hep B case, that those infected with Hep B may have a positive obligation to alert others not to share their razors, for example). This goes beyond the principles established in R v Dica and R v Konzani. The CPS Guidelines on prosecuting cases involving the sexual transmission of disease indicate that the appropriate use of condoms by a person living with HIV would ordinarily preclude a finding of recklessness – they do not (because the law does not require it) state that a person living with HIV is under an obligation to use a condom (or, of course, to disclose status).

Another problematic aspect of the decision is that appears to be a bad compromise. The plea was entered and accepted in part, it seems, to prevent E (the child complainant) to have to give evidence at a retrial. It is for this reason that what would otherwise have been a case involving alleged sexual offences was transmuted into one concerning offences against the person. This was arguably artificial, and (as the discussion above about the Court of Appeal’s comments about the nature of PM’s duty shows) has resulted in – it is suggested – flawed reasoning.

Finally, although it wasn’t addressed in the Court of Appeal’s judgment, there remains the question of knowledge and scientific evidence of transmission. What follows is speculative in the instant case, but important, I think, to bear in mind.

1. PM moved in with E and Z and their mother in September 2005. He was diagnosed with gonorrhoea in November 2005 and the children in December 2005. If there is any possibility that PM may have infected E and Z prior to his diagnosis, and before he had any reason to believe that he might be suffering from gonorrhoea, there was no case to answer (see R v Dica; R v Konzani).
2. If, as the Court of Appeal accepted (albeit because of the “artificial” nature of the settlement that was reached on plea to avoid retrial) that gonorrhoea may be spread manually as the result of poor manual hygiene, then questions should have been raised as to the possibility that the source of the infection may have been elsewhere. There appears to have been no scientific evidence adduced, and the prosecution did not – it appears – seek any. The CPS Guidelines make it clear that there needs to be compelling proof that the defendant is the source of a complainant’s infection – and (critically) that a guilty pleas should not be accepted unless the prosecution believes that there is sufficient evidence to prosecute. Cases involving HIV transmission have fallen because of this.

The Marangwanda case is unfortunate because it appears to be yet another example of the ways in which the ill-thought out approach of the courts to liability for the transmission of sexually transmissible diseases can – in the absence of clear thinking and understanding – have unintended effects.

Matthew Weait
23rd April 2009

Canada: Johnson Aziga and questions about the virological evidence

Here’s an excellent piece analysing flaws in the recent Johnson Aziga trial by Chris Morley, HIV Policy, Information and Publications Coordinator at George House Trust in Manchester, England. He writes this in a personal capacity.

He has had first-hand experience with some UK criminal HIV transmission cases, and contributed significantly to the HIV Forensics chapter of my book. He originally wrote this as a comment on my posting about the scientific evidence in the trial, but I thought it deserved a posting in its own right. He’s also written about the trial on the GHT website.

Johnson Aziga and questions about the virological evidence

by Chris Morley

Call a virologist

The defence lawyers failed to follow a key lesson from some recent English cases – which is to call a virologist, expert in HIV, as an expert witness, or at the very least commission an expert HIV virologist’s report to use as evidence.

Because the state called Dr Paul Sandstrom, director of the Public Health Agency of Canada’s national HIV and retrovirology laboratories as its scientific witness, there was a critical need to have an internationally respected independent expert HIV virologist giving evidence for the defence.

In well represented recent English cases, some level of expert HIV virologist involvement has led to a not guilty verdict, acquittal, case dismissed, and cases being abandoned. It makes a crucial difference to the outcome. It may not always cast enough reasonable doubt on all prosecution claims, but the English experience so far is all of prosecution failures where this is used, and usually of prosecution successes when it isn’t used.

From my reading of reports about the scientific evidence an expert virologist would have been able to question, or even demolish the assumptions and conclusions put forward by the prosecution.

Here’s the report, from The Hamilton Spectator, of the testimony of Dr Sandstrom:

“We were able to determine that all of the complainants and Aziga had a phylogenetically distinct form of HIV and that Mr. Aziga had the virus prior to contact with any of the women,” Sandstrom said. …..

Aziga and the women in the Hamilton infection cluster all had Clade A, which is rare in North America but endemic in Aziga’s native Uganda.

In this country, fewer than 2 per cent of those newly diagnosed with HIV have subtype A.

Phylogenetic analysis examines small differences in HIV genes by coding sequences of the HIV genome and comparing them to other HIV sequences in public databases.

HIV virologists can only determine the degree of similarity between two samples. They can’t produce a definitive match because unlike human DNA, HIV is not unique to an individual.

The analysis is also unable to determine the direction of transmission, Sandstrom said. So, theoretically, one of the women could have infected Aziga, instead of the other way around.

To resolve that issue, Sandstrom obtained a frozen blood-plasma sample drawn from Aziga after his HIV diagnosis 12 years ago. The specimen — collected before Aziga met any of the women — was phylogenetically analyzed and found to be nearly identical to the Hamilton infection cluster, comprising Aziga and the seven HIV-positive women.

“It means Mr. Aziga did not become infected by any of the women and that he had already been infected prior to contact with any of the women,” Sandstrom said.

No Proof

This does not fully address or prove transmission from Johnson Aziga at all – other explanations are at least a possibility, and need to be ruled out. Mr Aziga and the women complainants are not the only people in Canada with subtype A – there are over 1000 other people diagnosed with it and more who are undiagnosed. One or more of the others with HIV-A might have been the source of one or more women’s HIV.

Sandstrom did not consider it part of his job to explore this, or try to exclude this as a possibility. As the leading state HIV virologist he had a professional obligation to attempt to resolve this uncertainty and present the full picture. It would either have strengthened or weakened the prosecution case. Either way it needed checking.

Not my job to check

He was cross examined about this by the defence who argued that although Aziga and the women share a related virus, that did not mean that other persons, still unknown, might not also be carriers and part of the same transmission network. “It still remains, that your investigation does not rule out the possibility that there are other people ‘out there’ who are a part of the same infection cluster,” suggested the lawyer. Sandstrom said his investigation was “not directed at finding additional complainants or additional suspects,” but at providing confirmatory evidence for the footwork done by Hamilton police.

And the police, under cross examination, said it wasn’t their job either, to look for other possible sources of the women’s HIV.

Miscarriage of Justice and reversed burden of proof

This leaves me with serious concerns that there has been a miscarriage of justice. The defence is left to carry out an investigation, without police powers or resources, requiring the taking and testing of blood samples and complex and expensive scientific analysis, in an attempt to show there are other credible explanations. Does this not unfairly reverse the legal burden of proof?

Sexual history of complainants must be a central part of all transmission investigations

With HIV transmission cases, the proper police investigative practice of not looking into a rape complainant’s own sexual history, is often adopted. A woman’s sexual history is irrelevant to whether she was forced to have sex by someone; however it is critical to establishing which of her partners might have been the source of HIV in a consensual encounter. To attempt to prove X did it, you have to at least rule out A, B, C etc. And this at least can be proved conclusively with virology (HIV virology can prove someone didn’t transmit that HIV, but it can’t prove who did).

Rarely are the circumstances such that a complainat can be absolutely sure which of several partners might have been the source. The police are used to checking statements and seeking corroboration for everything. Why are claims about who transmitted HIV treated as if they cannot and must not be questionned? Why don’t the police routinely seek, and prosecutors demand, corroboration by ruling out all other possibilities?

For example, one of the women who died (H.C.) had three previous partners in recent years, two of whom were also migrants from Africa and, if HIV positive, likely also to have HIV-A. And an earlier date of infection from one of these men would better explain her surprisingly rapid development and death from Burkitt’s lymphoma, all apparently within 3 years or so of her supposed infection by him. (Reported here based on reports in The Hamilton Spectator )
And regarding the other women, see for example this article in The Hamilton Spectator.

Reasonable doubt opportunity wasted

With prosecution and defence expert witnesses contradicting each other, reasonable doubt would be raised far more strongly. Instead of calling an expert in HIV virology, the defence called Rafal Kustra, an associate professor of biostatistics with the Dalla Lana School of Public Health at the University of Toronto. He was not able to make much of an impact, saying he was “underwhelmed” by the level of analysis used by Ottawa scientists who concluded that Johnson Aziga and seven HIV- positive women carry viruses that are so closely related they can be described as a single “Hamilton transmission cluster.” He criticised the method used by Sandstrom and that was about it. He didn’t produce any new evidence, and wasn’t even invited by the defence to offer a different interpretation of the same facts, or say what further evidence was needed, and which questions need to be answered, before the prosecution’s case can become credible scientifically.

The defence barrister did criticise the prosecution’s scientific claims and failure to eliminate other potential sources of HIV. This does not carry any real weight with judge and jury – in legal terms it is not evidence, more an argument. The defence lawyer is not a scientific expert who can credibly contradict Canada’s head of HIV virology, no matter how right he may be. He tried, but didn’t call an expert virologist as a witness who could have made the argument convincing with fresh evidence and interpretation based on professional expertise.

An independent expert virologist might have been able to show, for one or more of the infected, scientific reasons why the prosecution are drawing the wrong conclusions and missing out vital evidence.

Establishing reasonable doubt is the job of the defence. Succeed, and the judge would then have pointed this out to the jury. The judge’s response to reasonable doubts should lead to a not guilty verdict, or acquittal, on one or more of the charges.

Not guilty verdicts and acquittals might not have produced justice, but there doesn’t seem to be much certainty of justice in this verdict, from what I have seen reported.

No-one knows for a scientific fact whether or not he did transmit HIV to the 7 people whom the prosecution claim he infected. This can never be proved with current scientific techniques. The essential virological analyses and testing of other partners, that might have shown the virological connections between the HIV samples could have more than one credible explanation, seem to have been omitted.

The apparent failure to eliminate from suspicion the women’s other / previous partners raises serious doubts about any scientific claims made that he was the source, because those claims seem based on only some of the potential scientific evidence.

Herd mentality

A herd mentality can develop in big trials and high profile cases. The pressures to secure a conviction are huge. In cases involving HIV transmission, some of the media behave like a baying mob. Police and prosecutors may become convinced they have their man and be unable to entertain any other possibility. We’ve much experience of this in England and this case has the hallmarks of another, but in Canada.

Dysfunctional justice?

It’s a case that shines a light on the Canadian justice performing badly in a major trial. It seems there are errors as much in the prosecution, police investigation and justice procedures, as well as tactical mistakes by the defence. He’s been five years in prison awaiting trial and this was his 6th team of lawyers. This case makes the Canadian justice system look dysfunctional. I hope it redeems itself at the appeal stage.