Corroboration in Scots Law

What it means and why it matters

Corroboration is one of the most important and most distinctive features of Scottish criminal law. It is also one of the least understood by people outside the legal system, which is unfortunate because it shapes the outcome of criminal cases in ways that matter enormously to everyone involved.

This page explains what corroboration is, what it requires, how it operates in practice, and why it has become the subject of significant debate in recent years.

The basic principle

In Scots law a person cannot be convicted of a criminal offence on the basis of the evidence of a single witness alone. There must be corroboration.

That means there must be at least two separate and independent sources of evidence that together establish the essential facts of the case. The evidence of one witness, however credible, however detailed, however compelling, is not by itself sufficient in Scots law to found a conviction.

This requirement applies to the essential facts of each charge. It does not mean that every single detail of the Crown's case must be corroborated. It means that the core elements — that a crime was committed and that the accused committed it — must be established by more than one independent source.

Why the requirement exists

The corroboration requirement is ancient in Scots law. Its roots lie in a concern that no person should lose their liberty on the word of one individual alone. That concern reflects something fundamental about the relationship between the state and the citizen. A system that allows conviction on a single uncorroborated account is a system that places enormous power in the hands of any individual willing to make an allegation.

The requirement for corroboration acts as a structural safeguard. It does not mean that complainers are disbelieved. It means that the legal system requires independent support for their account before it will deprive another person of their liberty.

That principle has proved controversial in recent years, particularly in sexual offence cases where by their nature there are often no witnesses other than the complainer and the accused. The argument that corroboration should be abolished or modified in such cases has been made repeatedly. So far the requirement has been retained in Scots law, though the debate continues.

What counts as corroboration

Corroboration does not require a second eyewitness to the act itself. It requires a second independent source of evidence that supports the essential facts. That second source can take many forms.

The significance of corroboration in practice

The corroboration requirement shapes how cases are built and how they are defended. For the Crown it means that before proceeding to prosecution there must be at least two independent sources of evidence. For the defence it means that identifying the absence or weakness of corroboration is often a central part of the defence case.

In practice many serious sexual offence cases involve limited physical or forensic evidence. The alleged offence took place in private. There are no independent witnesses. Forensic evidence may be absent, ambiguous or equally consistent with consensual activity. In such cases the Crown's ability to establish corroboration often depends on one of the less direct forms of evidence described above, or on the Moorov doctrine where multiple allegations are involved.

Understanding how the Crown is establishing corroboration in any given case is one of the most important questions a defence solicitor must address. If there is genuinely insufficient corroboration the case should not proceed to trial. If corroboration is weak or dependent on contested evidence that is a central argument for the defence.

The debate about abolition

In 2011 a review led by Lord Carloway recommended abolishing the corroboration requirement in Scots law. The argument was that the requirement was an outdated anomaly that prevented genuine victims from obtaining justice, particularly in sexual offence cases where the nature of the offending meant that corroboration was structurally difficult to obtain.

The proposal proved deeply controversial. The Law Society of Scotland, the Faculty of Advocates, and many legal practitioners argued strongly against abolition on the grounds that corroboration is a fundamental safeguard against wrongful conviction. Without it, they argued, the risk of convicting innocent people on the basis of a single uncorroborated account would increase significantly.

The proposal was not implemented. The corroboration requirement remains in Scots law. But the debate has not entirely gone away and the tension between the interests of complainers in serious cases and the safeguards available to the accused continues to shape how the law develops in this area.

What this means for people involved in cases

For anyone trying to understand a Scottish criminal case the corroboration question is often central. How did the Crown establish corroboration? What was the second source of evidence? Was that evidence strong or weak? Was it challenged effectively at trial?

In cases involving multiple complainers the Moorov doctrine is frequently the mechanism through which the Crown addresses the corroboration requirement. Understanding Moorov is therefore essential to understanding how many serious sexual offence cases in Scotland are built and defended. It is covered in detail on the next page.