While police reports in specific cases do not generally acknowledge the use of informers, police readily admit that many cases could not be solved without the aid of informers. The continued use of informers greatly depends upon their anonymity, because a practice of disclosure could endanger an informer's life. However, this anonymity or secrecy even regarding the use of an informer could jeopardize an accused's defense to the point of affecting trial outcome. This potential circumstance has caused both the Court of Appeal and the Home Office to exhort the police and prosecution not to withhold the fact of an informer's involvement where disclosure might have a bearing on the outcome of the case. Nevertheless, judicial decisions have shown the courts's reluctance to force disclosure of an informer's identity unless it is clearly necessary or could help to establish the defendant's innocence. The clearest circumstance where the secrecy of an informer's role could jeopardize a defense is when an informer acts as an agent of 'entrapment' for the defendant. This is particularly questionable when the informer is himself an operative in the criminal world. A number of recent cases sought to alleviate the accused's plight by excluding evidence obtained through entrapment. The Home Office has provided general guidelines on the use of informer participants, but the only sanction for their breach is internal discipline, a sanction that can only be applied against police officers, not informers. The greatest potential for curbing abuses in the use of informers appears to be improved control by senior police officials over the conduct of informer dealings. In each case, the benefit achieved must be weighed against the costs in public trust and the interests of justice encompassed in the rights of defendants. A total of 46 notes are listed.