He may also appoint the crown prince

The 1997 Constitution was the first constitution to be drafted by popularly elected Constitutional Drafting Assembly, and was popularly called the "People's Constitution".[28] The 1997 Constitution created a bicameral legislature consisting of a 500-seat House of Representatives (??????????????, sapha phutaen ratsadon) and a 200-seat Senate (???????, wuthisapha). For the first time in Thai history, both houses were directly elected.
Many human rights are explicitly acknowledged, and measures were established to increase the stability of elected governments. The House was elected by the first past the post system, where only one candidate with a simple majority could be elected in one constituency. The Senate was elected based on the province system, where one province can return more than one senator depending on its population size.
The two houses of the National Assembly have two different terms. In accordance with the constitution the Senate is elected to a six-year term, while the House is elected to a four-year term. Overall the term of the National Assembly is based on that of the House. The National Assembly each year will sit in two sessions an "ordinary session" and a "legislative session". The first session of the National Assembly must take place within thirty days after the general election of the House of Representatives. The first session must be opened by the king in person by reading a Speech from the Throne; this ceremony is held in the Ananda Samakhom Throne Hall. He may also appoint the crown prince or a representative to carry out this duty. It is also the duty of the king to prorogue sessions through a Royal Decree when the House term expires. The king also has the prerogative to call extraordinary sessions and prolong sessions at his discretion.
The National Assembly may host a "Joint-sitting" of both Houses under several circumstances. These include: The appointment of a regent, any alteration to the 1924 Palace Law of Succession, the opening of the first session, the announcement of policies by the Cabinet of Thailand, the approval of the declaration of war, the hearing of explanations and approval of a treaty and the amendment of the Constitution.
Members of the House of Representatives served four-year terms, while senators served six-year terms. The 1997 People's Constitution also promoted human rights more than any other constitutions. The court system (???, saan) included a constitutional court with jurisdiction over the constitutionality of parliamentary acts, royal decrees, and political matters.