Judges' Rules, with the inclusion of a caution on arrest of the right to silence, were not taken in by the government until 1978. However the rights were already well established by case law as was the necessity of no adverse comments, the principle being that the defendant does not have to prove his innocence – the burden of proof rests on the prosecution. However the right to remain silent "does not denote any single right, but rather refers to a disparate group of immunities, which differ in nature, origin, incidence and importance". Lord Mustill identified six rights contained within the umbrella term: There were a number of projects to modify the law, such as the 1972 Criminal Law Revision Committee. The committee recommended that inferences should be drawn from silence, but the committee report was strongly opposed. Certain changes were introduced with the Police and Criminal Evidence Act 1984 (commonly known as PACE), deriving from the Royal Commission on Criminal Procedure report of 1981; these introduced a right to have a legal representative during police interrogation and improved access to legal advice. The right to silence during questioning and trial was changed substantially in the 1990s. The right had already been reduced for those accused of terrorist offences, or questioned by the Serious Fraud Office or the Royal Ulster Constabulary, but in 1994 the Criminal Justice and Public Order Act modified the right to silence for any person under police questioning in England and Wales. Before the Act, the caution issued by the police varied from force to force, but was along the lines of: This is similar to the right to silence clause in the Miranda Warning in the US. PACE Code C, one of the codes of practice issued under PACE, was modified to specify a uniform wording for the caution, namely: In some circumstances, particularly if a suspect has requested legal advice but has not been allowed the opportunity to consult a solicitor, no adverse inferences may be drawn; in this scenario, the appropriate caution is amended to omit this possibility: Equivalent cautions are specified in Welsh. The 1994 Act, in addition to the amended codes of practice, was based on the 1972 Criminal Law Revision Committee report and the Criminal Evidence (Northern Ireland) Order 1988. It rejected the reports of the 1991 Royal Commission on Criminal Justice and the Working Group on the right to