The Preventive Detention Act (PD Act) is a law that allows authorities to take someone into custody based on suspicion or anticipation of future criminal activities or disturbances. It is an imprisonment that is putatively justified for non-punitive purposes, most often to prevent further criminal acts. The PD Act is allegedly justified for non-punitive purposes, and it supports human imprisonment where it is necessary for state purposes such as national defence, keeping the peace and maintaining public order, handling foreign affairs, etc.

The PD Act is distinct from conventional criminal prison, which is applicable in both a crisis and a calm scenario. Detained or arrested individuals are protected by Article 22 of the Indian Constitution. Preventive detention was practised in India even during the British era.

The PD Act is invoked by the police on habitual and notorious offenders to keep them locked in jail for a period of one year. It is applied against any person/individual with the intent that the person might change their behavior and mend their way of living after being released into society. However, the PD Act is a severe punishment to any common man, and to a habitual offender, it is not a serious punishment.

In some cases, the PD Act has been misused, leading to criticism from the judiciary. For example, the Telangana High Court expressed its anguish over what it called "the callous exercise of the exceptional power of preventive detention" by the detaining authorities and the Telangana state government. The court instructed authorities who initiate detention proceedings and confirmation authorities to be sensible while invoking the PD Act.