Illegally Obtained Evidence in UK Law

It is a well established rule of English law, which was recognised in Reg. v. Sang, that (apart from confessions as to which special considerations apply) any evidence which is relevant is admissible even if it has been obtained illegally. In Kuruma v. The Queen [1955] A.C. 197, Lord Goddard C.J. said, at p. 203:

The facts of this case, where on any view the constable concerned bent over backwards to try to assist the appellant in difficult circumstances, provides an example where exclusion under section 78 would not have been appropriate. The facts of this case, where on any view the constable concerned bent over backwards to try to assist the appellant in difficult circumstances, provides an example where exclusion under section 78 would not have been appropriate.

It is no part of a judge's function to exercise disciplinary powers over the police or prosecution as respects the way in which evidence to be used at the trial is obtained by them.

Fortunately, in both criminal and civil proceedings, courts can now adopt a less rigid approach to that adopted hitherto which gives recognition to the fact that there are conflicting public interests which have to be reconciled as far as this is possible.

It is frequent in matrimonial disputes for one party (in this case the wife) to suspect that the other party is about to destroy documents, or conceal information which is, or may be, relevant to the proceedings, and to do so with a view to preventing her from obtaining from the court the financial provision to which she claims to be entitled.

In exercising his discretion whether to admit the evidence of an undercover officer, some, but not an exhaustive list, of the factors that the judge may take into account are as follows: Was the officer acting as an agent provocateur in the sense that he was enticing the defendant to commit an offence he would not otherwise have committed? How active or passive was the officer's role in obtaining the evidence?

It seems to us, as a matter of principle, that, again in the absence of any defence on the particular facts, a claimant who establishes a right of confidence in certain information contained in a document should be able to restrain any threat by an unauthorised defendant to look at, copy, distribute any copies of, or to communicate, or utilise the contents of the document (or any copy), and also be able to enforce the return (or destruction) of any such document or copy.