regularly review their legislation in order to ensure that ir corresponds to the changing needs of society. In the field of civil and political rights, a State party is required to respect Covenant rights such as the right to a fair trial, to freedom of expression and freedom of religion, immediately from the date of entry into force of the Covenant, and to do so without discrimination. On the other hand, with regard to rights enshrined in the International Covenant on Economic, Social and Cultural Rights, it is generally understood that States parties may need time for the progressive implementation of these rights and to adapt relevant legislation in stages; moreover, constant efforts are needed to ensure that distinctions that were reasonable and objective at the time of enactment of a social security provision are not rendered unreasonable and discriminatory by the socio-economic evolution of society. Finally, we recognize that legislative review is a complex process entailing consideration of many factors, including limited financial resources, and the potential effects of amendments on other existing legislation. In the context of the instant case, we have taken due note of the fact that the Government of the Netherlands regularly reviews its social security legislation, and that it has recently amended several acts, including the Health Insurance Act. Such review is commendable and in keeping with the requirement, in article 2, paragraphs 1 and 2, of the Covenant, to ensure the enjoyment of Covenant rights and to adopt such legislative or other measures as may be necessary to give effect to Covenant rights. 116