“No one shall be held guilty of any criminal offence on account of any act or omission 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 one that was applicable at the time the criminal offence was committed.”
“106. The Court therefore concludes that since the X v Germany decision a consensus has gradually emerged in Europe and internationally around the view that application of a criminal law providing for a more lenient penalty, even one enacted after the commission of the offence, has become a fundamental principle of criminal law. It is also significant that the legislation of the respondent State had recognised that principle since 1930 (see Article 2 and 3 of the Criminal Code, cited in paragraph 32 above). 107. Admittedly,Article 7 of the Convention does not expressly mention an obligation for Contracting States to grant an accused the benefit of a change in the law subsequent to the commission of the offence. It was precisely on that basis of that argument relating to the wording of the Convention that the Commission rejected the applicant’s complaint in the case of X v Germany. However, taking into account the developments mentioned above, the Court cannot regard that argument as decisive. Moreover, it observes that in prohibiting the imposition of “a heavier penalty… than the one that was applicable at the time the criminal offence was committed”, paragraph 1 in fine of Article 7 does not exclude granting the accused the benefit of a more lenient sentence, prescribed by legislation subsequent to the offence. 108. In the Court’s opinion, it is consistent with the principle of the rule of law, of which Article 7 forms an essential part, to expect a trial court to apply to each punishable act the penalty which the legislator considers appropriate. Inflicting a heavier penalty for the sole reason that it was prescribed at the time of the commission of the offence would mean applying to the defendant’s detriment the rules governing the succession of criminal laws in time. In addition, it would amount to disregarding any legislative change favourable to the accused which might have come in before the conviction and continuing to impose penalties which the State – and the community it represents – now consider excessive. The Court notes that the obligation to apply, from among several criminal laws, the one whose provisions are the most favourable to the accused is a clarification of the rules on the succession of criminal laws, which is in accord with another essential element of Article 7, namely the foreseeability of penalties. 109. In the light of the foregoing considerations, the Court takes the view that it is necessary to depart from the case-law established by the Commission in the case of X v Germany and affirm thatArticle 7(1) of the Convention guarantees not only the principle of non-retrospectiveness of more stringent criminal laws but also, and implicitly, the principle of retrospectiveness of the more lenient criminal law. That principle is embodied in the rule that where there are differences between the criminal law in force at the time of the commission of the offence and subsequent criminal laws enacted before a final judgment is rendered, the courts must apply the law whose provisions are most favourable to the defendant.”
“80. What conclusions can be drawn from this domestic case law on how English courts should deal with Strasbourg decisions on the interpretation of the ambit of a provision of the Convention itself, as opposed to an ECtHR decision on how a provision in the Convention is to apply to particular factual circumstances? We think that the following principles are clear: (1) It is the duty of the national courts to enforce domestically enacted Convention rights. (2) The ECtHR is the court that, ultimately, must interpret the meaning of the Convention. (3) The UK courts will be bound to follow an interpretation of a provision of the Convention if given by the Grand Chamber as authoritative, unless it is apparent that it has misunderstood or overlooked some significant feature of English law or practice which, properly explained, would lead to that interpretation being reviewed by the ECtHR when its interpretation was being applied to English circumstances. (4) The same principle and qualification applies to a “clear and constant” line of decisions of the ECtHR other than one of the Grand Chamber. (5) Convention rights have to be given effect in the light of the domestic law which implements in detail the “high level” rights set out in the ECtHR. (6) Where there are “mixed messages” in the existing Strasbourg case law, a “real judicial choice” will have to be made about the scope and application of the relevant provision of the Convention.”