On the other hand, the effects of these principles on the democratic institutions in a given country will widely depend not only on their constitutional and legal dimension and practical realisation, but mainly on the model of separation of powers in that country, i.e. on whether the political system is dominantly parliamentarian, presidential or organised in the form of a mixed system. The separation of powers has also been endangered by technocratic powers claimed by governments over parliaments. In the modern era, parliaments can be classified into three categories: first, policy-making parliaments, with significant autonomy and active impact on policy (US Congress, for example); second, policy–influencing parliaments, which by reacting to executive initiatives can transform policy and third, executive dominated parliaments, with marginal influence on policy. Parliaments must defend their right to control governments and to have an active role in decision-making.