The merits of the theory of separation of powers are stated below.
1. Protection of Liberty and Rights:
The theory of separation of powers protection to the liberty and rights of the individual, and protects him from different of despotism and oppression.
2. Increase in Government's Efficiency:
As powers are distributed among the government departments, these departments gain deep knowledge of the matters they with, and become more efficient.
3. Limited Government:
As powers are distributed among different depart these departments enjoy only limited powers. This prevents rise of dictatorship.
4. Prevents Abuse of Power:
Separation of powers accompanied by check and bal is an effective check against abuse of power and arrogance of power.
This theory, though adopted by most countries, has not escaped criticism. It has criticized not only as impossible but also as undesirable. According to Sabine, "Montes was guilty of oversimplification. He united his theory to a hasty and superficial analysis the constitutional principles of liberty." Finer said that it was futile to rigidly apply the theory of separation of powers to modern condition.
The theory of separation of powers has been attacked on the following grounds.
1. Wrong Reading of British System:
By the time Montesquieu developed his theory of separation of powers, there had come into being the Cabinet system of govern" There was not in Britain then separation of powers. On the contrary, there was 'concentration of responsibility.' Having witnessed the British people enjoying liberty, Montesquieu wrongly concluded that in Britain there was separation of powers. He misread British politics.
2. Not Fully Possible:
This theory is not fully possible. The executive has some role in rule-making, and the legislature also performs some judicial functions. For example, impeachment which is judicial in nature is done by the legislature.
3. Administrative Complications:
Separation of powers results in administrative complications. It becomes difficult to forge cooperation, coordination and harmony among the organs of government. The smooth working of modem governments demands not so much separation of powers as 'co-ordination' of powers.
4. Confusion and Deadlock:
Separation of powers leads to jealousy, suspicion and friction among the organs of government. While producing disharmony and confusion, it may paralyse the administration. As a result, the administration often fails to take quick decisions even at a time of crisis.
According to Finer, the theory of separation of powers throws "governments into alternating conditions of coma and convulsion." Another scholar is of the view that "separation of powers means confusion of powers."
5. Inequality of Powers:
This theory is based on the principle of equality of powers, but this principle is flawed. In the parliamentary system, the legislature which represents the people is most powerful while the executive is most powerful in the presidential system.
6. Not the Sole Factor of Liberty:
Separation of powers may contribute to liberty, but it is not the only factor of liberty. Liberty also depends a lot on the psyche of people, their outlook, their political awareness, customs and traditions, fundamental rights, rule of law, independence of judiciary and economic equality.
7. Balance Disturbed:
The government, performing various important functions, has become increasingly powerful. Besides being the problem-solver and crisis-manager, it is also required to provide welfare to people. All this has made the executive very powerful, and disturbed the balance among the three organs of government. Planning, security and welfare demand not so much separation of powers as their 'fusion'.
8. A Misnomer:
This theory is a misnomer, because what it means is separation of function, not separation of powers.
Increased concern for welfare and security has been responsible for transfer of more powers to the executive, though liberty is significantly dependent upon balance among the three organs of government. In an ideal system, there should be equal interest in the liberty of the individual as well as in his welfare and the security of state. This, no doubt, would require a strong government but this would also call for separation of powers coupled with check and balance.