The main reasons for granting an independent status to the judiciary are as follows: 

First, Judiciary's independence is linked to its role as the watchdog in a democracy. It monitors and maintains the checks and balances over the other arms of the government. Thus judiciary emerges as a mediator when any organ of the government exercises 'excess power' which tends to violate the larger societal or individual interest. 

Second, in order to ensure that constitutionally guaranteed freedoms such as freedom to speak in public or peacefully assemble, are interpreted as per the true constitutional philosophy, judiciary has been kept free from any external pressures. 

Third, Judiciary acts as a guardian of fundamental rights which are constitutionally granted to every citizen in India. Our Constitution grants us unique rights such as: Civil and political rights- e.g. the right to life; right to freedom of discrimination 2 based on religion, race, caste, sex or place of birth. Economic, social and cultural rights- e.g. freedom to practice any religion; protection of interests of minorities. An independent and impartial Judiciary has empowered Indian citizens and performed this role. 

Fourth, in the domain of criminal law as well, independence of judiciary is linked to the granting of a fair trial to the accused. This becomes extremely important even when the accused are foreign nationals or persons who have committed crimes against the state, e.g. terrorists. 

Lastly, independence of judiciary is vital for the respect of due process of law. Due process of law means that the State must respect all the legal rights that are owed to a person and conform to the norms of fairness, liberty, fundamental rights etc. Only an independent judiciary can make this concept operational. 

Therefore independence of judiciary remains a vital and core principle even in the modern democracy.