needed to avoid that under international law a single conduct although consisting of an infliction of severe mental or physical pain or suffering - be considered criminal when it is carried out by private individuals for private purposes. Such conduct is not of international concern and is therefore not covered by the Convention. In other words, the state official requirement constitutes what one could term the quid pluris, transforming an ‘ordinary’ criminal offence into an international crime. It simply serves the purpose of precluding every single wicked act carried out by private individuals against other private individuals from being elevated to the international level.” (at p 190) Similarly, Burgers and Danelius (above) observe (at p 1) that UNCAT “does not deal with cases of ill-treatment which occur in an exclusively non-governmental setting. It only relates to practices which occur under some sort of responsibility of public officials or other persons acting in an official capacity.” 72. Other writers go further in addressing the particular issue with which we are concerned. Reference has been made above (at para 31) to the commentary by Nowak and McArthur in which they conclude that the conduct of rebel, guerrilla or insurgent groups which exercise de facto authority in certain regions or of warring factions in so-called “failing States” would fall within the scope of article 1. Similarly, the editors of Cassese’s International Criminal Law, 3rd ed (2013) state: “Finally, under the UN Torture Convention, the ‘pain and suffering’ that is a necessary ingredient of torture must be inflicted ‘by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity’. The need for this sort of participation of a de jure or de facto state official stems from: i) the fact that in this case torture is punishable under international rules even when it constitutes a single or sporadic episode; and ii) the consequent necessity to distinguish between torture as a common or ‘ordinary’ crime (for example, torture of a former intimate partner by a sadist) and torture as an international crime covered by international rules on human rights.” (at p 133) 73. Professor Gaeta returns to this issue in Clapham and Gaeta, Torture by Private Actors and “Gold Plating” the Offence in National Law, in Guzman et al (eds), Arcs of Global Justice: Essays in Honour of William Schabas, (OUP 2018), Ch 15, which is a dialogue between Professor Gaeta and Professor Andrew Page 36