A/HRC/4/20 page 12 leader.82 The range of offences involved invites an inquiry into the underlying normative rationale, and suggests that problems of non-compliance have remained widespread. It is clear that a subjective approach to this important issue is not viable, in the sense that a vast array of offences might understandably be classified by any given individual or Government as being among the “most serious”. But such an approach would render the relevant international law standard meaningless. As a result a systematic and normatively persuasive response is essential. 41. The basic requirement was first introduced in article 6 (2) of the International Covenant on Civil and Political Rights (ICCPR): “In countries which have not abolished the death penalty, sentence of death may be imposed only for the most serious crimes in accordance with the law in force at the time of the commission of the crime and not contrary to the provisions of the present Covenant and to the Convention on the Prevention and Punishment of the Crime of Genocide. This penalty can only be carried out pursuant to a final judgement rendered by a competent court.” 42. This provision supplemented that prohibiting the arbitrary deprivation of life, in article 6 (1): “Every human being has the inherent right to life. This right shall be protected by law. No one shall be arbitrarily deprived of his life.”83 43. It has been much commented upon that neither term - “arbitrarily deprived” or “most serious crimes” - is further defined in ICCPR. In this regard, various sources are illuminating. And while the travaux préparatoires are but a supplementary means of interpretation, they do assist in understanding the ordinary meanings of these terms. 44. One insight that emerges from the travaux of article 6 of ICCPR is that the concepts of arbitrariness and of the “most serious crimes” serve to add a requirement of substantive justice to the requirements of formal legality and due process. An early version of the article stated that it “shall be unlawful to deprive any person of his life” with the one exception being upon “conviction of a crime for which this penalty is provided by law”.84 Notably, this version, which implied that the legality of an execution would be determined solely within the domestic legal order, was rejected. A number of delegates pointed out that it would permit what amounted to arbitrary killing to be masked by the trappings of law.85 Various substantive limits on the scope of death penalty laws were thus introduced, including a prohibition of arbitrary deprivations of life (with “arbitrarily” meaning either “illegally” or “unjustly”86), a prohibition of death sentences for other than the “most serious crimes”, and a requirement that any such deprivation be consistent with ICCPR and the Convention on the Prevention and Punishment of the Crime of Genocide.87 To determine whether a particular offence falls among the most serious crimes, thus, requires interpretation and application of the relevant international law rather than of the subjective approach opted for within a given State’s criminal code and sentencing scheme. 45. Another key insight to be drawn from the travaux relates to the apparent imprecision of the terms used to define the scope of the right to life. The report of the Secretary-General to the General Assembly on the draft Covenant identified three views that had been advanced during the drafting of ICCPR. The first was that the right to life should be expressed in absolute terms