Overcoming objections to the admissibility of lie-detection evidence

One day on Mount Olympus, satirist to the gods Momus noticed an important oversight in the making of man: “Why have you forgotten to put in a window so we can see what the humans are thinking?”. A recent case from the USA suggests that functional magnetic resonance imaging (fMRI) of the brain might open an aperture through which our honesty can be peeped at. Will the cortex replace the court? Or is the fMRI a forensic mirage along with polygraphs and truth serums? And why exactly, of all the obscure expert evidence English courts readily admit, is lie-detection verboten?

Late last year, the US Court of Appeals Sixth Circuit in USA v Semrau [2012] WL 3871357 grappled for the first time with the admissibility of fMRI evidence of a defendant’s veracity in criminal proceedings. Semrau was convicted of three counts of fraud by a Tennessee district court after being refused permission to rely on fMRI evidence showing that he had not, in general, lied when denying the frauds. fMRIs measure brain activity by monitoring fluctuations in blood oxygenation and flow in response to neural activity. The more active an area of the brain becomes, the more it needs oxygen and blood. Expert witness Dr Laken testified that he was able to chart those areas of Semrau’s brain involved in deception and was, therefore, able to give an opinion as to whether he was lying.

Test failed

The Sixth Circuit upheld the district court’s decision to exclude Dr Laken’s testimony. Expert scientific evidence must, in America, pass a stringent four-part test devised by the US Supreme Court in Daubert v Merrell Dow Pharmaceuticals 509 US 579 (1993).

First, fMRI lie-detection had to be shown to be testable; second, the technique had to have been subjected to peer-review and publication; third, the analysis must have a known or potential error rate along with standards controlling its operation; and fourth, the technique must be generally accepted in its scientific field. The Sixth Circuit held that fMRI lie-detection fell on the third and fourth Daubert hurdles. The error rates were “mathematically, statistically and scientifically incorrect” and, while there might have been compelling independent laboratory testing supportive of fMRI lie-detection, there was no ‘real-world’ research on the technique’s uncovering duplicity when a person is in jeopardy of losing something dear to him. Dr Laken’s own research also had a very high rate of mistakenly identifying truth tellers as liars.

For the Sixth Circuit, Dr Laken’s evidence was inadmissible novel scientific evidence on the basis of the prejudicial failure to allow the prosecution to participate in the testing; the fact that only ‘general’ non-deceptiveness rather than particular deceptiveness could be detected; the perceived unreliability of the tests; and the lack of a consensus regarding fMRI lie-detection among neurologists. The Sixth Circuit even doubted whether the technique’s reliability could be tested as only Semrau knew whether he was lying.

But every science must have its first day in court. DNA evidence was once sniffed at; now it is commonplace. The laboratory evidence supporting fMRI lie-detection arguably approaches the compelling results of studies supporting polygraphs. Polygraph evidence has an 81 per cent to 91 per cent accuracy rate according to the American National Academy of Sciences; fMRI analysis has produced, in laboratory settings, accuracy rates of 86 per cent to 93 per cent: see USA v Semrau, [2010] WL 6845092 at paragraph ten. And within America a patchwork of 20 state courts along with over half of all federal courts permit polygraph evidence.

Trial distorted

In contrast to America’s relative openness to polygraph lie-detection, English courts are, at first glance, closed to all lie-detection techniques. The authority for this strict rule is Fennell v Jerome Property Maintenance Ltd, The Times, 26 November 1986 (QBD) a case involving the admissibility of truth-drugs, and by implication mechanical tests like polygraphs or fMRIs. Unlike the Sixth Circuit in Semrau, Tucker J in Fennell was not concerned with lie-detection’s reliability; nor did he appear to be aware of earlier cases in the 1950s and 1960s where truth-drug evidence had been admitted (see J. Crim. L. 2012, 76(3), 232-253). He was instead troubled that truth-drug evidence might “distort… the normal process of trial” by usurping the court’s role and would introduce inadmissible previous consistent statements. Fennell, a first-instance 1980s civil case without precedent that related solely to truth drugs, is the only authority for the inadmissibility of polygraphs, narcoanalysis, fMRI analysis and brain electrical activation profile (BEAP) evidence in England. Fennell is perhaps a weak bar to expert lie-detection entering the courtroom.

So what is the problem with lie-detection? With the exception of the US, strict doctrinal issues have troubled this and other common-law jurisdictions far more than lie-detectors’ reliability. In R v Béland [1987] 2 S.C.R. 398, the Canadian Supreme Court provided a batch of doctrinal objections to polygraphs. Such evidence, the majority held, amounted to hearsay and to expert evidence that would trample on the common-knowledge rule (telling a jury what it should be presumed to have knowledge of) and the ultimate-issue rule (experts’ determining an issue that should be left to the jury). Polygraph readings also constituted inadmissible previous consistent statements, violated the rule against oath-helping and introduced particular rather than merely general evidence of good character.

However, the objections in Béland arguably no longer apply and did not, in any event, convince two of the seven Canadian Supreme Court judges.

Ultimate issue

Through attrition, the ultimate-issue rule has been worn away to “a matter of form rather than substance” (per Lord Taylor CJ in R v Stockwell (1993) 97 Cr App R 260, 266) and hearsay evidence is now routinely heard. The admissibility of previous consistent statements has been significantly widened suggesting that principles of fairness and relevance should now trump the old exclusionary rule. Indeed, the rationale behind the inadmissibility of previous consistent statements is to prevent an account being given an air of credibility merely through repetition. Polygraphs are not adduced as previous consistent statements but as evidence of witnesses’ physiological responses when making a statement. And how can a positive polygraph or fMRI reading amount to good character evidence? One’s moral fibre is not at stake but simply one’s bodily reactions?

As for the injunction against oath-helping, what bearing does this ‘curious point of legal history’ (per Wilson J (dissenting) in Béland [28]) have on the modern trial? Oath-helping’s prohibition ended compurgation, where a litigant proved his case merely by arranging for a series of compurgators to swear oaths in his favour. Unlike the mediaeval compurgator, the Twenty-first Century expert witness is not simply regurgitating an oath but is cross-examined on evidence that is open to rebuttal. Should a pre-modern rule be invoked to exclude, in the interests of fairness, compelling expert evidence of a defendant’s veracity?

Moreover, English courts do not require error rates and consensuses regarding scientific techniques as do their US counterparts. Expert evidence on ear prints, held by the Court of Appeal to be admissible, would simply not have passed the stringent Daubert test (R v Dallagher [2003] 1 Cr App R 12). In R v Luttrell [2004] 2 Cr App R 520. Lip-reading evidence, “not susceptible’ as it is ‘to…scientific discipline” (ibid. at [34]), was, nevertheless, deemed admissible by the Court of Appeal. English courts’ more liberal attitude to expert evidence might soon come to an end: the Law Commission’s proposed changes to expert evidence’s admission would lead to a tighter Daubert-like reliability test for expert evidence. Until then, expert lie-detection evidence might be considered reliable, more reliable perhaps than quasi-scientific evidence from ear-print scrutinisers (Dallagher), lip-readers (Luttrell) and footwear fanciers (T (Footwear mark evidence) [2011] 1 Cr App R 85).

As for the common-knowledge rule, although Lawton LJ in R v Turner [1975] 1 QB 834 scorned expert evidence on “how ordinary folk who are not suffering from any mental illnesses are likely to react”, might jurors need assistance in determining credibility? Should expert evidence of witnesses’ truthfulness be reserved only for extreme cases involving abnormal individuals (see Toohey v Metropolitan Police Commissioner [1965] AC 595).

A hotchpotch of folklore, pop psychology and gut feelings is behind common-sense tests of veracity. Many preconceptions of a liar’s demeanour are simply wrong. Fidgeting, moving one’s head, smiling, leg or foot motions, gesticulating, rubbing, pinching and scratching do not, according to research, indicate lying. Indeed, liars are more likely not to exhibit what intuition will whisper to us is a ‘tell’.

Consistent approach

There are undoubtedly problems with mechanical lie-detection. Polygraphs often fail to identify lying psychopaths. Polygraphs and fMRIs can be cheated; and neither can account for the lie that has crystallised over time into a ‘truth’ for the liar. As with all expert testimony, robust cross-examination can unearth these evidential deficiencies.

Lie-detectors’ limitations aside, is English law’s prohibition on the use of polygraphs sustainable when they will be used to monitor offenders? The Offender Management Act 2007 has created mandatory polygraph testing for specified sex-offenders as part of their licence conditions. Failure to comply with a polygraph condition or a finding of deception might ultimately result in recall to prison. Worryingly, although sex-offenders’ physiological responses and statements made during polygraph testing cannot be used as evidence against them in criminal proceedings, the 2007 Act does not prohibit their use against offenders in civil proceedings or against others in any legal proceedings.

Mandatory lie-detection was held not to offend released offenders’ rights to privacy during the programme’s pilot (R (on the application of C) v Ministry of Justice [2009] EWHC 2671 (Admin)). But does the apparent prohibition against a defendant’s relying on a polygraph reading violate his right to a fair trial? There is an irony in English law’s view on expert lie-detection: polygraphs can be used to return you to prison but cannot be used to keep you out. Indeed, the Strasbourg Court has held that there was no violation of article 6 where a defendant was prevented from relying on polygraph evidence (A v Germany [1986) 6 EHRR CD 360).

The exclusion of lie-detection evidence is a doctrinal tangle. Is English law an eccentric defendant away from a clearer position on polygraphs or fMRI analysis? Perhaps. Until then, there remain, as far as English courts are concerned, no windows into men’s souls.