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:

(i) 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.

(ii) Direct Election of the Government: In the second system, the Government is elected by the people directly, because the voters know the party in whose favour they are casting their votes. Thus, the people vote for the party whom they wish to form a Government.

(iii) Formation of Government is easier: In this system, it becomes easy for the Head of the State to decide which party should be invited to form the Government. The Head of the State (President, King or Governor-General) invites the leader of the majority party to form the Government. In this way the majority party forms the Government. If the majority party loses the majority support in the legislature, the Head of the State invites the opposition party to form the Government.

(iv) It ensures a strong Government and continuity of Policy: Because of the stability of the Government in a bi-party system, ii is strong and it can pursued good policy continuously. In contrast to this, the cabinets change very often multi-party system. The Government becomes weak and there is no continuity in the policy. In a bi-party system, the Government is stable and it can formulate long term plans for the welfare of the people. It can also ensure its goodwill to foreign countries.

Demerits:

(i) 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.

(ii) Limited choice before the voters: When there are only two parties before the electorate, they have to elect one out of the two parties, even if they do not like both the parties. In this way, the electorate loses its freedom of choice. In case there are more than two parties, the choice for the voters becomes wide.

(iii) The Prestige of the legislature is lowered: In a bi-party system, the majority party supports the cabinet. The Prime Minister has a special influence over the Parliament because he is the leader of the House by virtue of his position as the leader of the majority party. With the help of his majority party he can get the Bills, budget, policies and treaties passed in the way he likes.

(iv) Dictatorship of the Majority Party: In this system the dictatorship of the majority party is established and it cares little for the opposition, because it enjoys a majority in the Parliament.

Functional or occupational representation is a protest against the system of territorial or geographical representation. In modem States the usual basis of representation is territorial.

Disdvantages:

Advantages:

i. The system of representation based upon classes, professions, occupations, or other groupings of society is not of recent origin. Mirabeau, at the time of the French Revolution, declared that a Legislative Assembly ought to be a mirror of all the interests of society.

ii. The system of functional representation is commonly known as the Soviet system. The geographical or territorial system of representation was replaced in Soviet Russia by a system based on the vocational principle, i.e., workers, farmers, professional men and other classes choose their own representatives without regard to territorial areas.

iii. There are two divergent groups who advocate occupational representation from different motives. The Communists support it, because it centres the voter’s attention upon his work relationships and forces him to think in proletarian terms. The non- Communists, on the other hand, advocate it because of their disgust with the present system of electing legislators from single-member constituencies.

Proportional representation is a type of electoral system that decides the make-up of a parliament by allocating seats on the basis of the number of votes each party received.

Single transferable vote system: The Single transferable vote (STV) is a system of preferential voting designed to minimize wasted votes and provide proportional representation while ensuring that votes are explicitly expressed for individual candidates rather than for party lists. It typically achieves this by using multi-seat constituencies (voting districts) and by transferring all votes that would otherwise be wasted to other eligible candidates.

STV initially allocates an elector's vote to his or her most preferred candidate and then, after candidates have been either elected or eliminated, transfers surplus or unused votes according to the voters' stated preferences.

List system: List System is another method of securing proportional representation. This method also operates in multiple-member constituencies. Different parties put up lists of as many candidates (each) as number of members to be elected. Thus, if seven persons are to be elected, each party will put up a list of seven candidates in the preference in which they would like to be elected. The voters vote of the quota (less than half being ignored, and more than half taken as one), that party will have its first three candidates in the list elected.

The role of political parties are mentioned below: 

i. It makes the working of parliamentary government possible. A parliament consists of the representatives of the people. The political parties organize these representatives on party lines. The electorate chooses their representatives on the basis of their party affiliation. The party which gets the majority of votes forms the government and runs the state and the other parties in the legislature constitute the opposition and try to find fault with the government, thus making it more responsible.

ii. Political Parties formulate public policies. Each political party fights the election to achieve its objectives incorporated in their political manifesto. Soon after the election the majority party forming the government seeks to formulate its policies of administration on the basis of promises made in the election manifesto. These policies are made keeping in mind the interest of general public.

iii. Education: The political parties educate public opinion through their propaganda. They publish newspapers, magazines, journals and other printed literature for popularizing their programmes and politics. Moreover, they have a host of speakers who explain and defend party programmes through Press and Platform.

iv. Link between the Government and the People: The political party belonging to the majority group in the legislature serves to maintain a link between the government and the people. Its rank and file explain and popularize the policies, pursued by the government. The political organization maintains a continuous connection between the elected representatives and thus makes the government really representative.

v. Monitor the Opposing Party in Power. Parties also serve as critical watchdogs for the public. The adversarial relationship between the major parties ensures that the party out of power will keep a close eye on its opponent and notify the public of any wrongdoing or policy misstep.

vi. Political parties provide political stability. The political parties in more than one way unite, simplify and stabilized the political process of the country. The destabilizing forces of localism, regionalism, section, interests and geographical situations are tackled by political parties by making these parts of their party ideology thus pacifying the disintegrating forces and inducing cohesion.

Limitations:

i. Periodic elections - One of the limitations to the Sovereignty of Parliament is periodic elections. It does not matter how long the parliament is mandated by law to exist. At some point, the law allows that there should be elections to renew the mandate of the parliamentarians, some of whom may lose their seat.

ii. Power of the Prime Minister - Another limitation to the Sovereignty of Parliament is the power of the Prime Minister to dissolve parliament. This can happen before the end of the lawful term of parliament. When this happens, there has to be a new election and the face of the parliament may not be the same as the previous one.

iii. Public Opinion - Another limitation is the existence of public opinion. The public can bring pressure to bear on the parliament to pass or not to pass certain laws.

iv. Membership of International Organizations - The membership of countries to other international organizations can serve as a limitation to the powers of parliament. For example, before Britain voted to leave the European Union, any law passed by the British parliament that conflicts with a law passed by the European parliament becomes subservient to the European Union law.

v. Constitutional checks - In countries that have written constitutions, the constitution specifically puts a limit on the powers of the parliament.

vi. Procedural limitations - Parliament is a well regulated institution where procedures must be followed to the letter in the carrying out of their functions. The fact that these parliamentary procedures cannot be sidetracked without consequences, one can say it serves as a limitation to its supremacy.