Bi - party system is a party system where two major political parties dominate the government. One of the two parties typically holds a majority in the legislature and is usually referred to as the majority or governing party while the other is the minority or opposition party.

Merits:

 Government becomes more stable: The Government is more stable in a bi-party system, because the party which has a majority in the legislature forms the Government and the other party acts as opposition. Coalition Governments are not formed in a bi-party system. If the ruling party loses the majority in the legislature, the Cabinet tenders its resignation. In such an eventuality, the opposition party forms the Government. It becomes the ruling party and the party which was hitherto for the ruling party, becomes the opposition party.

Demerits:

 Dictatorship of the Cabinet: In a bi-party system the dictatorship of the cabinet is established as in the case in England, because it has the majority support in the Parliament. In such a situation, the ruling party does not care much for the opposition.