The political system has evolved over time along with culture and tradition. It had started with local rulars or chieftians to Desi followed by monarchy and now we have Constitutional Monarchy.
Utill the arrival of Zhabdrung Ngawang Namgyel from Tibet there was no systematic form of government in Bhutan. He has introduced the dual administration where Desi is the secular (Administrative) head and Je Khenpo (Cheif Abbot) as the religious head.
But there was a great change with the form of government from 1907 with the appointment of Sir. Ugyen Wangchuck as the first monarch by the people of Bhutan unanimously. The king has replaced the administrative head that's Desi, but the post of Chief Abbot is still retained where the dual administration is still continued. After that Bhutan was ruled by successive monarchs of the Wangchuck Dynasty.
The first move towards democratic governance was with the instituting National Assembly (Tsogdue) in 1953 by third king Jigme Dorji Wangchuck. Every gewog will have their elected member to represent National Assembly. And its the platform where the elected members enact laws and also discuss national issues.
In 1963 the Royal Advisory Council (Lodroe Tsogdey) was established. Its the body that links between the King, Council of Ministers, and people. And also they can advise King and ministers on National Issues and also assure the projects are implemented successfully.
In 1981 the Dzongkhag Yargay Tshogdoe (District Development Assembly) was established and Gewog Yargay Tshochung (Gewog/Block Development Assembly) was instituted in 1991.
Major decentralization happened in 1998 with devolution of power to the cabinet ministers. Whereby most of the government works are done by the prime minister and cabinet ministers.
In 2001 the committee chaired by the chief justice was formed on the command of the fourth king to draft the constitution of Bhutan. We have 2 houses; the upper house (National Council) have 25 members. 1 each from every district elected by people and 5 will be appointed by King. And in lower house National Assembly we have 47 members and all the members are elected by people.
And we do have 2 rounds of election for National Assembly whereby in the primary round people can vote for the best political party and only top 2 party qualifies for the general round. In the general round for the best candidate and whichever party gets the highest seat forms the government and other forms opposition. So basically we have only 2 political parties in the hall.
In 2008 we had the first election with the introduction of constitutional monarchy. We had only 2 political parties; Druk Phuensum Tsogpa (DPT) headed by Jigme Yeoser Thinley and People's Democratic Party (PDP) led by Sangay Nidup of which DPT formed the first democratically government with 45 seats out of 47 seats.
But in 2013 at the time of the second election, the political party increased to 5 including DPT and PDP. And the new Parties are Druk Nyamrup Tsogpav(DNT), Bhutan Kuen-Nyam Party (BKP), and Druk Chirwang Tsogpa (DCT). But all 3 new parties were out of the race in the primary election and this time PDP formed the government and DPT was in opposition.
In 2018 the third election time, DCT got dissolved and there were only 4 political parties. And this time PDP and BKP were out in the primary round. And this time DNT led by Dr. Lotey Tshering formed the govt and DPT is still in opposition.
The organs of the Bhutanese government comprise the Legislature, Judiciary, and the Executive. The ruling political party, the opposition, and the National Council now forms the legislative body.