Who can apply for constitutional remedies?

Any aggrieved person whose fundamental rights have been violated can avail constitutional remedies by filing a writ petition before the Supreme Court or the High Court.(( Articles 32 and 226, Constitution of India, 1950.)) 

For habeas corpus(( Sunil Batra v. Delhi Administration, 1980 AIR 1579.)) and mandamus(( Bandhua Mukti Morcha v. Union of India, 1984 AIR 802.)), people other than the aggrieved person can also file a petition to seek a particular remedy. 

It is important to understand that not all fundamental rights are available to all people. For instance, the right to equal opportunity in employment(( Article 16, Constitution of India, 1950.)) and freedom of speech and expression¹ are available only to citizens. On the other hand, fundamental rights such as the right to life(( Article 21, Constitution of India, 1950.)) and the right to be treated equally before the law² are available to all people, irrespective of whether they are citizens or non-citizens. A person can file a writ petition seeking constitutional remedies to enforce any fundamental rights which are available to them.

1. Article 19(1)(a), Constitution of India, 1950. [↩]
2.  Article 14, Constitution of India, 1950. [↩]