(CUKC) for people born or naturalised in either the United Kingdom or one of its colonies. Provision was also made in certain circumstances for citizenship to be acquired by descent from a CUKC, or by registration. Despite the fact that the Channel Islands and the Isle of Man were neither part of the United Kingdom proper nor were colonies of it, article 33 of the Act provides that when the Act mentions colonies, it must be construed as including references to these Islands. Islanders were allowed, upon personal wish and not as a compulsory denomination, to be presented as "citizens of the United Kingdom, Islands and Colonies". This does not constitute a separate category of citizens but is merely a formal denomination. Reform of the Act, and subsequent Acts Between 1962 and 1971, as a result of popular opposition to immigration by Commonwealth citizens from Asia and Africa, the United Kingdom gradually tightened controls on immigration by British subjects from other parts of the Commonwealth. The Immigration Act 1971 introduced the concept of patriality, by which only British subjects with sufficiently strong links to the British Islands (i.e. the United Kingdom, the Channel Islands and the Isle of Man) had right of abode, the right to live and work in the United Kingdom and Islands. Most of the 1948 Act was replaced by the British Nationality Act 1981 with effect from 1 January 1983. The Act today The only significant provision of the Act to survive today is section 3, which concerns the extra-territorial jurisdiction of the criminal courts over crimes committed by British subjects overseas. Generally, British criminal law does not apply to things done overseas, but there are some exceptions for acts done abroad by British subjects, such as murder. Section 3 restricted the scope of this jurisdiction to CUKCs (except in respect of crimes that would be against UK law even if committed by aliens). This was necessary so that, for example, a Canadian citizen who committed murder in Canada could not be prosecuted for it in a British court instead of in Canada. As modified by section 51 of the British Nationality Act 1981, section 3 now restricts this jurisdiction to British citizens, British Overseas Territories citizens, British Overseas citizens and British Nationals (Overseas). Note, however, that section 3 is subject to any subsequent legislation to different effect, such as section 72 of the Sexual Offences