become law. The legislature cannot override a pocket veto. Some veto powers are limited in their subject matter. A constitutional veto only allows the executive to veto bills that are unconstitutional; in contrast, a "policy veto" can be used wherever the executive disagrees with the bill on policy grounds. Presidents with constitutional vetoes include those of Benin and South Africa. Legislative veto A legislative veto is a veto power exercised by a legislative body. It may be a veto exercised by the legislature against an action of the executive branch, as in the case of the legislative veto in the United States, which is found in 28 US states. It may also be a veto power exercised by one chamber of a bicameral legislature against another, such as was formerly held by members of the Senate of Fiji appointed by the Great Council of Chiefs. Veto over candidates In certain political systems, a particular body is able to exercise a veto over candidates for an elected office. This type of veto may also be referred to by the broader term "vetting". Historically, certain European Catholic monarchs were able to veto candidates for the papacy, a power known as the jus exclusivae. This power was used for the last time in 1903 by Franz Joseph I of Austria. In Iran, the Guardian Council has the power to approve or disapprove candidates, in addition to its veto power over legislation. In China, following a pro-democracy landslide in the 2019 Hong Kong local elections, in 2021 the National People's Congress approved a law that gave the Candidate Eligibility Review Committee, appointed by the Chief Executive of Hong Kong, the power to veto candidates for the Hong Kong Legislative Council. Balance of powers In presidential and semi-presidential systems, the veto is a legislative power of the presidency, because it involves the president in the process of making law. In contrast to proactive powers such as the ability to introduce legislation, the veto is a reactive power, because the president cannot veto a bill until the legislature has passed it. Executive veto powers are often ranked as comparatively "strong" or "weak". A veto power may be considered stronger or weaker depending on its scope, the time limits for exercising it and requirements for the vetoed body to override it. In general, the greater the majority required for an override, the stronger the veto. Partial vetoes