It is a line - perhaps the line - most regularly invoked by corroboration's defenders, in their opposition to Kenny's Bill. Nobody should be convicted on the evidence of one person, advocates thunder. Requiring a second source of evidence holds witnesses to account, sparing the innocent from falling prey to credible but fraudulent court testimony.
Advocates of abolishing corroboration, on the other hand, tend to have little to say about the position of accused persons. Their main focus are complainers - often described as victims - whose complaints are never heard by courts, because the requirement of evidence from two sources means that some aspect of the charge is insufficiently corroborated. Can it be right that serious criminal offences with profound effects on the well-being of citizens may be committed with impunity?
Superficially, these are both compelling lines of argument. Who wants the innocent to be convicted? Who wants the guilty to walk free? So should we abolish corroboration or not? Regular readers of the blog will know I have swithered on this one. I thought I should explain why - and hopefully the explanation might help others to make up their minds where they lie. The problem is that both proponents of abolition and retention make important points, and speak to important values.
Let's start with the easy admissions. One: corroboration represents a safeguard for accused persons. In some cases, a very effective safeguard, in that it excludes their conduct from any criminal liability. What's more, it preserves us from the dangers of convicting people solely on the basis of false confessions and means that a scheming witness cannot jail you simply on their own word.
Two: from complainers' perspective, corroboration is a very blunt instrument. Just one example: a woman regularly beaten up by her ex-spouse falls victim to his jealous aggression yet again when he appears at her flat. When questioned, he denies being there. There is no other evidence connecting him to the scene. Although reduced physically to welts and bruises, the identify of her attacker is uncorroborated, however well she might know his face, and the case is dropped. Even for corroboration's greatest defenders, this is a problematic outcome.
For me, the key question on abolishing corroboration is, does retention or abolition satisfy a cost-benefit analysis, taking into account the interests both of complainers and accused persons? It is generally recognised that the rule represents a significant barrier to bringing some kinds of cases to court. But is corroboration really a significant safeguard from the accused's perspective? Does it really protect us from miscarriages of justice, and the lies of a beguiling but false witness? If it is and it does, that might make one more skeptical about eliminating the rule from our criminal justice system. If, by contrast, corroboration does not really do these things, and represents only a limited safeguard and a substantial barrier to justice, its abolition might begin to look more attractive.
My main problem with the defence of corroboration that is being offered by Hamilton, Cullen and their colleagues in the legal world is that it relies on a - to my mind inflated - understanding of what the corroboration rule of today actually requires. We know that corroboration does not require the Crown to produce "two witnesses" implicating the accused. We know that the rule does not require two sources of evidence substantiating "all claims against the accused", but only the essential facts which are that (i) the criminal offence was committed and (ii) that it was the accused who committed it. So what is necessary?
One of the most important but overlooked features of the contemporary doctrine of corroboration is that it does not require that corroborating evidence actually points decisively to the guilt of the accused. Evidence from secondary sources, equally consistent with the Crown's charge, or the accused's version of events, can corroborate the direct evidence of witnesses (Fox v. H M Advocate). As usual, all of this is bound up in alienating legal complexities, and its significance may not immediately be apparent, so let's illustrate this with an example.
Thomas, Kristian and Mark are acquaintances who live in a sparsely-populated, rural part of Scotland. Mark is found dead, shot, his body abandoned where he was killed, on a heather heath under the sky. Thomas approaches the police, telling them that he saw Mark and Kristian having an argument that morning, and observed the latter gun the former down. On investigating, Kristian denies killing Mark, claiming that he was nowhere near the field in question that morning, but was instead out rough-shooting in another part of the neighbourhood.
Neither victim nor alleged attacker bear traces of the other man's DNA about their person. There is no evidence of past animus or threats being transacted between the two. A search of Kristian's house yields up no gun matching the bullet which inflicted Mark's injuries, and no evidence that he recently acquired and may have disposed of such a weapon. Kristian's muddy walking boots bear surface traces of soil of the same composition as the heath where the body was found - but the area of countryside where he claims he was walking is of the same composition. On account of the dense heather underfoot, no prints matching Kristian's tread could be found anywhere near the body. While forensic evidence of gunshot residue is found on Kristian, he explains that this derives from his hunting expedition, not from shooting Mark.
This looks like a formally corroborated case. Our starting point is Thomas' witness statement, confirming the essential facts that (i) he saw the accused at the locus (ii) killing the dead man. But what about the corroboration? The muddy boot is capable of putting the accused at the scene, but it is also consistent with his not implausible innocent explanation of being elsewhere in the territory. The gunshot residue - which as I understand it, at this time cannot be matched to a particular firearm - presents evidence consistent with the idea that Kristian shot Mark, but equally consistent with the claim that he took a pop at a passing grouse on the moor as he claims.
But for evidence equally consistent with Kristian's innocence, the case comes down entirely to one man's word. Once the requirements of corroboration are satisfied, it's all a matter for the jury. In our hypothetical case, everything would seem to turn on whether or not Thomas is regarded as a credible and reliable witness on whose word to convict Kristian beyond reasonable doubt.
Because corroboration does not require the corroborating evidence to point decisively towards the guilt of the accused, or require it to be more consistent with guilt than innocence, cases may already rely to a significant extent on the testimony of one - potentially credible-seeming and dishonest - witness. It may be that scheming Thomas knew Kristian's habits, and bumped off Mark himself. The idea, regularly invoked by its defenders, that the abolition of corroboration introduces this risk into the system radically overstates the extent to which corroboration really acts as a safeguard against it.
Yes, the rule excludes cases from court where there is only one witness. Where there is one witness plus circumstantial evidence capable of innocent or incriminatory interpretation, however, the dissembling witness is given ample opportunity by the corroboration rule to lie through their teeth in the witness box, in an attempt to put the accused away.
Short version: convictions can already effectively rely, in the current system, on the evidence of a single witness. This shouldn't be surprising. Corroboration is a quantitative test, not a qualitative one. It doesn't generally enquire into the quality of the supporting evidence: concerned primarily with counting the number of sources. In these circumstances, the rule provides at most a wicker shield against miscarriages of justice.
All of which leads me to the conclusion that the advantages of the corroboration rule have been wildly overstated by the doctrine's defenders. Yes, it forms a barrier against a very simple kind of injustice, but as shields go, its material is pitted and cracked, strained and broken by a century's worth of judicial interpretation. It's nice rhetoric for Lord Cullen to appeal to the centuries over which corroboration has served Scotland. The reality, however, is that the current corroboration rule little resembles the classical formulation of two witnesses speaking directly to the guilt of the accused. It's contemporary defenders cannot credibly appeal to such antiquities, in defence of its current, compromised form.
If the modern conception of corroboration represents only a limited safeguard for accused people, and a substantial barrier systematically preventing cases of domestic and sexual assault from reaching court, I struggle to see how retaining it strikes the right balance. The rule is very effective at excluding some kinds of offences and some kind of offenders from court. This might be justified if it served a significant, competing purpose offering a substantial protection for accused people from wrongful conviction. But it doesn't.
Important outstanding issues remain. Convictions on the basis of confession evidence alone remain problematic. What harm could there be, in including a provision in the Bill to the effect that confession evidence alone is insufficient in law to convict an accused person? I also find the Scottish Human Rights Commission's idea of giving judges a limited discretion to refuse to put concluded prosecution cases to juries for decision a compelling one. Why wait till after conviction and appeal, to determine that "no reasonable jury" could convict an accused person on the basis of the evidence led?
But corroboration? It's a battle-scarred old shield, but despite the ineptness and confusion of many advocating its abolition, including the Cabinet Secretary, I'm not convinced that it retains even half the virtues attributed to it, in its current shape. A half-century of judicial skirmishes in the Court of Appeal have chipped away its veneer, and splintered its substance. It's time, I think, to hang the old girl up for good.