After World War I, Czechoslovakia established itself and as a republic and democracy with the establishment of the Constitution of 1920. The constitution was adopted by the National Assembly on 29 February 1920 and replaced the provisional constitution adopted on 13 November 1918.
The constitution was modelled after constitutions of established Western democracies that had stood the test of time. Among its most notable influences were those of the United Kingdom, United States and France. The system of government the constitution introduced made Czechoslovakia the most westernized of all of the central and eastern European nations on the verge of World War II.
The constitution created a parliament but also a president and cabinet, sharing powers of executive branch. Beneath them was a judiciary that was advanced with many levels of courts delegated for various types of cases.
The parliament, the National Assembly, was bicameral. The Chamber of Deputies consisted of 300 members elected for 6 years. The Senate consisted of 150 members elected for 8 years. Suffrage was exercised by all citizens, of both sexes, over the age of 21 for elections to the lower chamber; and over the age of 26 for elections to the senate. Candidates for the lower chamber had to be at least 30 years of age; and for the senate, at least 45 years of age.
The parliamentary system that was installed created a complicated system of proportional representation, with relatively few constituents for each representative. It was possible to get a seat with as little as 2.6 percent of the vote. This allowed for a great variety of political parties to emerge, with no clear front runner or leading political entity. A typical Chamber of Deputies during the First Republic had well over 10 factions represented. With so many parties as part of the national forum, it was all but impossible for one party to win the 151 seats needed for a majority. No party came close to being able to govern alone until the Communist Party was able to secure nearly fifteen percent of the seats in the 1948 elections. Since it was so hard to secure a majority, the government was at times stalled out and unable to effectively legislate.