is an important objective which can, in principle, permit the limitation of certain rights. To be justifiable, however, the imposition of such a limitation must satisfy various requirements. Assuming that the right is capable of limitation and that the limiting measure is imposed within the bounds of certain procedural requirements, it must be necessary to achieve a particular counter-terrorism objective. To be necessary, a rational link must exist between the limiting measure and the pursuit of the particular objective.40 The existence of a rational link will normally be accepted if the measure logically furthers the objective, although more evidence of this connection might be necessary if such a link is not plainly evident.41 In that regard, and for the purpose of determining the importance of a particular measure’s objective, it will be instructive to determine: how the measure is linked with the countering of an actual or potential threat of terrorism against the State; the measure’s contribution to international and regional frameworks on counter-terrorism as well as, subsidiarily, its contribution to other national interests of the State.42 (d)  Example of permissible limitations The requirements for a valid limitation of rights can be illustrated in the context of incitement to terrorism and freedom of expression, a subject considered further in chapter III. Prohibiting incitement to terrorism involves a limitation on the ability of persons to express themselves as they wish. Any prohibition against incitement must therefore comply with the requirements for a legitimate limitation on rights and freedoms: the limitation must thus be prescribed by law; be in pursuit of a legitimate purpose; and be both necessary and proportional. The first requirement, that any limitation must be prescribed by law, means that the prohibition against incitement should take the form of a provision within legislation. As to legitimate purpose, proscribing incitement to terrorism is consistent with the protection of national security or public order, which are both set out as legitimate grounds for the limitation of freedom of expression in article 19 (3) of the International Covenant on Civil and Political Rights. Prohibiting incitement to terrorism is also consistent with its article 20 (2), which requires States to prohibit any advocacy of national, racial or religious hatred that constitutes incitement to discrimination, hostility or violence. The final requirement of necessity and proportionality is relevant to the way in which the proscription is expressed in the legislation and how it is applied. The law prohibiting incitement to terrorism must be expressed 25