It was the idea of Montesquieu to entrust the different functions of the government to the separate branch. It is quite helpful to prevent the apathy of the government in democracy towards its citizens.
Executive, Legislative and Judiciary are the three main functions of the government. For proper functioning of the democracy and democratic form of government. It is quite useful to a handful to handle each function of the government by the three separate forms of government.
Executive: President of India, Union Council of Ministers, Governor of each state, Council of Ministers at the state level, Bureaucracy are the part of the Executive. The executive is mainly responsible to execute the programme and policies of the government. The executive is also responsible for various policies like education policy, defence policy, foreign policy, manufacturing policy..etc.
The executive is mainly responsible for maintaining law and order, defending the country, promoting the welfare of the people of the country.
Legislative: Union Parliament and State Legislative Assembly are the two main legislative bodies in the country. These two bodies are mainly responsible to frame law on their respective domain. The members of Lok Sabha as well Legislative Assembly of state and union territory are elected by the people on the basis of universal adult franchise.
Union parliament as well as State legislative Assembly frame law for the welfare of people in their respective domain as mentioned in the Schedule VII of the Indian constitution.
Judiciary: Supreme Court of India, High court of various states, Lower courts are the part of the Judiciary wing of the government. Judiciary is mainly responsible for the interpretation of the law.
Since India follow a parliamentary form of government, where watertight separation is not possible because the executive is the part of the legislature. In Parliamentary form of government council of ministers are necessarily to be a member of Parliament / State Legislative Assembly. This is not the case with the presidential form of government.
Separation of power is more effective in Presidential form of like in the USA where Executive, Judiciary and Legislature are independent. In the presidential form of government separate election are held to elect the president of the country as well as the Legislative.
All the three organs of the government function independent of one another.
Article 50 of the Indian constitution says State shall take steps to separate Judiciary from Executive in public service of the state
CrPC Act 1973 made the provision that takes away criminal jurisdiction from Executive Magistrate.
The theory of separation was propounded by the Montesquieu.
The Theory of Separation of power is essential to avoid the misuse of power, despotism, the concentration of power.
The presidential form of government seeks to achieve complete separation of power between the Executive, Judiciary and Legislative organs of a state.