The fundamental right under Article 21 is one of the most important rights provided under the Constitution which has been described as the heart of fundamental rights by the Apex Court in Unni Krishnans case. The objective of the fundamental right under Article 21 is to prevent encroachment upon personal liberty and deprivation of life except according to procedure established by law. It clearly means that this fundamental right has been provided against the state only.
The scope of Article 21 was a bit narrow till 1950s as it was held by the Supreme Court in A. K. Gopalan vs. State of Madras Case 1950 that there was no guarantee in our Constitution against arbitrary legislation encroaching upon personal liberty. Hence if a competent legislature makes a law providing that a person may be deprived of his liberty in certain circumstances, the validity of law could not be 
challenged in a court of law on the ground that the law is unreasonable, unjust, and unfair
The majority judgement in Gopalan case was, however, overturned in Maneka Gandhi v. Union of India Case 1978 that led to the following propositions: § Art 19 and 21 are not watertight compartments. On the other hand, the expression of ‘personal liberty’ in Art 21 is of the widest amplitude, covering a variety of rights of which some have been included in Art 19 and given additional protection. Hence, there may be some overlapping between Art 19 and 21. § Thus, a law coming under Art 21 must also satisfy the requirements of Art 19. In other words, a law made by state, which seeks to deprive a person of his personal liberty, must prescribe a procedure for such deprivation which must not be arbitrary, unfair, or unreasonable
The expanded scope of Article 21 has been explained by the Apex Court in the case of Unni Krishnan v. State of A.P. and the Apex Court itself provided the list of some of the rights covered under Article 21 on the basis of earlier pronouncements and some of them are listed below:
- The right to go abroad.
- The right to privacy.
- The right to shelter.
- The right to social justice and economic empowerment.
- The right against solitary confinement.
- The right against hand cuffing.
- The right against delayed execution.
- The right against custodial death.
- The right against public hanging.
- Doctors assistance
- Protection of cultural heritage.
- Right of every child to a full development.
- Right to pollution free water and air.
Thus it is clear that the provision of Article 21 was constructed narrowly at the initial stage but the law in respect of life and personal liberty of a person was developed gradually and a liberal interpretation was given to these words. New dimensions have been added to the scope of Article21 from time to time. It imposed a limitation upon a procedure which prescribed for depriving a person of life and personal liberty by saying that the procedure must be reasonable, fair and such law should not be arbitrary, whimsical and fanciful.