A writ is a legal document that is issued by the Supreme Court to direct a person or authority to take a specific action. These writs serve as legal orders to protect the fundamental rights of citizens from being violated. According to Collins Dictionary, a writ is a legal document that instructs a person to do a particular thing. This means that a writ can be used to compel someone to take a specific action, such as to stop violating someone's rights or to perform a particular duty.

Who Can Issue A Writ?

Writs can be issued by the Supreme Court of India under Article 32 (for fundamental rights) of the Indian Constitution and by the High Courts of India under Article 226 (for fundamental rights as well as constitutional rights) of the Indian Constitution.

Against Whom A Writ Can Be Issued Under Article 32 ?

Article 32 empowers the Supreme Court to issue writs for the enforcement of fundamental rights guaranteed by the Constitution against any person or authority who violates an individual's fundamental rights, including government authorities, private individuals/entities, or persons working under government authority.

Types Of Writs-

There are indeed five types of writs that can be issued under Article 32(2) of the Indian Constitution, which are:

1. Habeas Corpus,
2. Mandamus,
3. Prohibition,
4. Quo Warranto,
5. Certiorari.

Habeas Corpus -

Habeas Corpus is a legal term that comes from England and means "you may have the body" in Latin. It's related to Article 21 and 22 of Indian Constitution. Essentially, it's a writ that allows a person who's been arrested or detained to appear before a judge or court to ensure that their detention is legal and to protect their fundamental rights. 

For example, if someone like Mr. X is arrested and his family believes that he's being held without a good reason, they can use a writ of Habeas Corpus to require the police to give evidence for his detention. If the judge determines that the detention is unjust, then Mr. X will be released. However, if the judge decides that there are good reasons for Mr. X's detention, then he'll have to stay in custody.

Circumstances When Habeas Corpus Cannot be Issued: 

• The detention is lawful.
• The case is being prosecuted for failure to comply with a legislative or judicial mandate.
• A competent court authorized the detention.
• The jurisdiction of the court on detention is ultra vires
  

Some Important Landmark Judgements-

ADM Jabalpur v. Shivakant Shukla, also known as the Habeas Corpus case, was decided by the Indian Supreme Court on April 28, 1976, by a bench of five judges, namely, Chief Justice A.N. Ray, and Justices H.R. Khanna, M.H. Beg, Y.V. Chandrachud and P.N. Bhagwati.

The Supreme Court's verdict in the Habeas Corpus case was that the writ of Habeas Corpus could not be suspended even during an emergency. However, by a majority decision of 4:1, the court held that during an emergency, fundamental rights, including the right to life, could be suspended. Justice H.R. Khanna was the lone dissenter in the case, and his judgment is widely regarded as a landmark in the history of Indian jurisprudence.

(In 2017, the Indian Supreme Court made a decision in a case called K.S. Puttaswamy v. UOI. They decided to overrule a previous decision that was made in a case called ADM Jabalpur. Justice D.Y. Chandrachud, along with three other judges (Justice J.S. Khehar, Justice R.K. Agarwal, and Justice S. Abdul Nazeer) stated that the ADM Jabalpur case was wrong or mistaken.)

Kanu Sanyal vs District Magistrate Darjeeling, the Supreme Court of India held that the detention of Kanu Sanyal was illegal and that the writ of Habeas Corpus was a fundamental right that could not be suspended even during a state of emergency.

Rudal Shah vs State of Bihar, the Supreme Court held that Habeas Corpus is a fundamental right and a powerful remedy to secure the release of a person who has been unlawfully detained. The court also ruled that the writ can be filed not only by the detainee but also by any person acting on their behalf, widening its scope. This decision established important legal principles that guide courts in matters of personal liberty and fundamental rights.

State of J&K v. Mian Abdul Qayoom, Justice D. Y. Chandrachud has emphasized the vital importance of the writ of Habeas Corpus in protecting individual liberty and upholding the rule of law. He has stressed that the writ is a precious and undeniable feature of the legal system and that it plays a critical role in preventing the abuse of power by the State. According to him, the writ of Habeas Corpus is not only a procedural safeguard but also a substantive right essential for the protection of individual freedom and dignity.

Conclusion-

Habeas Corpus is a legal writ that protects an individual's fundamental rights by ensuring that their detention is legal.. It is a fundamental right and plays a critical role in preventing abuse of power by the state. The writ can be filed not only by the detainee but also by any person acting on their behalf.

References-

Additional District Magistrate, ... vs S. S. Shukla Etc. Etc on 28 April, 1976 (indiankanoon.org)
Kanu Sanyal vs District Magistrate, Darjeeijng ... on 11 September, 1973 (indiankanoon.org)
Rudul Sah vs State Of Bihar And Another on 1 August, 1983 (indiankanoon.org)
Mian Abdul Qayoom vs State Of J&K And Others on 7 February, 2020 (indiankanoon.org)
Justice K.S.Puttaswamy(Retd) vs Union Of India on 26 September, 2018 (indiankanoon.org)
Writ of Habeas Corpus: History, Scope, and Landmark Judgements (legalbites.in)
What is Habeas Corpus and how to use it - iPleaders
Habeas Corpus - Features, Cases, UPSC Notes for Polity. (byjus.com)
Constitution of India - Wikipedia
Lakxmikant
M.P. Jain
Writ: Definition in Law, Types, and Examples (investopedia.com)