18 Legal Digest of International Fair Trial Rights “(e) to have the free assistance of an interpreter if he cannot understand or speak the language used in court.” Article 7 “(1) 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 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 omission which, at the time when it was committed, was criminal according to the general principles of law recognised by civilised nations.” Article 1 of Protocol 4 “No one shall be deprived of his liberty merely on the ground of inability to fulfil a contractual obligation.” Article 1 of Protocol 7 “(1) An alien lawfully resident in the territory of a State shall not be expelled therefrom except in pursuance of a decision reached in accordance with law and shall be allowed: “(a) to submit reasons against his expulsion, “(b) to have his case reviewed, and “(c) to be represented for these purposes before the competent authority or a person or persons designated by that authority. “(2) An alien may be expelled before the exercise of his rights under paragraph 1.a, b and c of this Article, when such expulsion is necessary in the interests of public order or is grounded on reasons of national security.” Article 2 of Protocol 7 “(1) Everyone convicted of a criminal offence by a tribunal shall have the right to have his conviction or sentence reviewed by a higher tribunal. The exercise of this right, including the grounds on which it may be exercised, shall be governed by law. “(2) This right may be subject to exceptions in regard to offences of a minor character, as prescribed by law, or in cases in which the person concerned was tried in the first instance by the highest tribunal or was convicted following an appeal against acquittal.”