Saturday, October 08, 2011

Fruit of the poisoned tree

When may evidence obtained 'downstream' from improperly obtained evidence be admissible? By downstream I mean that the finding of the challenged evidence occurred as a consequence of the improper obtaining of the other evidence.

For example, if the defendant, under improper questioning, gives information to the police about a witness who could vouch for him, and the police consequently question that witness and obtain evidence incriminating the defendant, how should the court decide whether the incriminating evidence is admissible? Facts like this were considered in HM Advocate v P (Scotland) [2011] UKSC 44 (6 October 2011). This is a companion case to that considered in my note yesterday.

The position in domestic Scots law is that if the evidence could be led without reference to the improperly obtained evidence it would not be treated as inadmissible by reason of it having been found as a consequence of the improperly obtained evidence: Lord Hope at 17, citing Lawrie v Muir 1950 JC 19. Similarly, in England and Wales under s 76(4) and 78(1) of PACE 1978 all the circumstances must be considered and the consequential evidence is not invariably excluded: at 18.

As far as Strasbourg jurisprudence went, there was no definitive decision but guidance could be obtained from Gäfgen v Germany (2011) 52 ECHR 1 (noted here on 3 July 2008, Chamber, and Grand Chamber on 25 June 2010): Lord Hope at 22. No rule of automatic exclusion of such consequential evidence has been established 23.

The Supreme Court found some assistance from Canada: Thomson Newspapers Ltd v Canada (Director of Investigation and Research) [1990] 1 SCR 425, where the distinction was made between evidence created by impropriety, and evidence that may have gone undetected but for the impropriety but which nevertheless existed independently.

This was consistent with the conclusion Lord Brown reached 27:

" ... there is no absolute rule that the fruits of questioning of an accused without access to a lawyer must always be held to be a violation of his rights under article 6(1) and 6(3)(c) of the Convention. It is one thing if the impugned evidence was created by answers given in reply to such impermissible questioning. The leading of such evidence will be a breach of the accused's Convention rights unless there are compelling reasons to restrict the right of access: Cadder [v HM Advocate [2010] UKSC 43], para 55. It is another thing if the evidence existed independently of those answers, so that those answers do not have to be relied upon to show how it bears upon the question whether the accused is guilty of the offence with which he has been charged. So far as the accused's Convention rights are concerned, there is no rule that declares that evidence of that kind must always be held to be inadmissible. The question whether it should be admitted has to be tested, as in domestic law, by considering whether the accused's right to a fair trial would be violated by the leading of the evidence."
Lords Dyson, Kerr and Matthew Clarke agreed with Lord Hope, as did Lord Brown in a separate judgment. Lord Brown drew attention to how the admissibility balancing decision would be made in England and Wales under s 78(1) of PACE.

See also the attenuation approach in R v Wittwer (discussed here 6 June 2008), and occasions where a consequential link may be dispensed with but evidence nevertheless excluded: R v Ogertschnig (discussed here 26 October 2008). Improprieties may taint evidence without there being a consequential link, and as the present case shows, improprieties may be irrelevant notwithstanding such a link.