of how the law limits their rights; and (b) the law must be formulated with sufficient precision so that individuals can regulate their conduct.35 Moreover, any criminal law proscription must also comply with the principle of non-retroactivity. Article 15 of the International Covenant on Civil and Political Rights requires, in this regard, that any provision defining a crime must not criminalize conduct that occurred prior to its entry into force as applicable law. Likewise, any penalties are to be limited to those applicable at the time that any offence was committed and, if the law has subsequently provided for the imposition of a lighter penalty, the offender must be given the benefit of the lighter penalty.36 (b)  In the pursuance of a legitimate purpose The permissible legitimate purposes for the interference vary depending on the rights subject to the possible limitations as well as on the human rights treaty in question. They are national security, public safety, public order, health, morals, and the human rights and freedoms of others.37 The important objective of countering terrorism is often used as a pretext to broaden State powers in other areas.38 Offences which are not acts of terrorism, regardless of how serious they are, should not be the subject of counter-terrorist legislation. Nor should conduct that does not bear the quality of terrorism be the subject of other counter-terrorism measures, even if undertaken by a person also suspected of terrorist crimes. Again, this requirement is reflected within various international and regional documents on the promotion and protection of human rights while countering terrorism.39 (c)  Necessity and proportionality What is often referred to as “necessary in a democratic society” is an additional safeguard which requires States to demonstrate that the limitations do not impair the democratic functioning of society. In practice, this means that they must meet the test of necessity and the requirement of proportionality. So any limitation on the free enjoyment of rights and freedoms must be necessary in the pursuit of a pressing objective, and its impact on rights and freedoms strictly proportional to the nature of that objective. As a general matter, given the impact of terrorism on human rights, security and the functioning of various aspects of international and domestic societies, there is no doubt that the countering of international terrorism 24