"(1) Where, in a case of a long-term or short-term prisoner -- (a) the whole or any part of his sentence was imposed for a sexual offence committed before30th September 1998 , and (b) the court by which he was sentenced for that offence, having had regard to the matters mentioned in section 32(6)(a) and (b) of theCriminal Justice Act 1991 , ordered that this section should apply."
"(1) No one shall be held guilty of a criminal offence on account of any act or admission which did not constitute a criminal offence under national or international law at the time when it was committed, nor shall a heavier penalty be imposed than the one that was applicable at the time the criminal offence was committed. (2) This article shall not prejudice the trial and punishment of any person for any act or admission which at the time it was committed was criminal according to general principles of law recognised by civilised nations."
"(1) So far as it is possible to do so, primary legislation and subordinate legislation must be read and given effect in a way which is compatible with Convention rights. (2) This section (a) applies to primary legislation and subordinate legislation whenever enacted, (b) does not affect the validity, continuing operation, or enforcement of any incompatible primary legislation and (c) does not affect the validity, continuing operation, or enforcement of any incompatible subordinate legislation, if, disregarding any possibility of revocation, primary legislation prevents removal of the incompatibility."