are less vulnerable to override than package vetoes, and political scientists who have studied the matter have generally considered partial vetoes to give the executive greater power than package vetoes. However, empirical studies of the line-item veto in US state government have not found any consistent effect on the executive's ability to advance its agenda. Amendatory vetoes give greater power to the executive than deletional vetoes, because they give the executive the power to move policy closer to its own preferred state than would otherwise be possible. But even a suspensory package veto that can be overridden by a simple majority can be effective in stopping or modifying legislation. For example, in Estonia in 1993, president Lennart Meri was able to successfully obtain amendments to the proposed Law on Aliens after issuing a suspensory veto of the bill and proposing amendments based on expert opinions on European law. An amendatory veto Worldwide Globally, the executive veto over legislation is characteristic of presidential and semi-presidential systems, with stronger veto powers generally being associated with stronger presidential powers overall. In parliamentary systems, the veto power of the head of state is typically weak or nonexistent. In particular, in Westminster systems and most constitutional monarchies, the power to veto legislation by withholding royal assent is a rarely used reserve power of the monarch. In practice, the Crown follows the convention of exercising its prerogative on the advice of parliament. International bodies : The five permanent members of the United Nations Security Council have an absolute veto over Security Council resolutions, except for procedural matters. Every permanent member has used this power at some point. A permanent member that wants to disagree with a resolution, but not to veto it, can abstain. The first country to use this power was the USSR in 1946, after its amendments to a resolution regarding the withdrawal of British troops from Lebanon and Syria were rejected. : The members of the EU Council have veto power in certain areas, such as foreign policy and the accession of a new member state, due to the requirement of unanimity in these areas. For example, Bulgaria has used this power to block accession talks for North Macedonia, and in the 1980s, the United Kingdom (then a EU member) secured the UK rebate by threatening to use its veto power to stall legislation. In addition, when the Parliament and Council delegate legislative