The decision makes it legal for the terminally ill to decide against using life support systems to continue living, and frees the doctors and families of those who slip into incurable comas to halt such measures, in the patients' best interest.
Terminally-ill patient can execute an "advance medical directive" or a "living will" to refuse medical treatment.
The bench laid down guidelines for those cases when there is no advanced directive.
The court directives on this will prevail until the Centre brings a legislation.
The Supreme Court had in 2011 recognised passive euthanasia in what has become known as the Aruna Shanbaug case by which it had permitted withdrawal of life-sustaining treatment from patients not in a position to make an informed decision.
Justices Sikri, Chandrachud and Ashok Bhushan gave concurring judgments with different reasons.
It involves adjustment of some medical support which will then hasten the death of a person, who has been declared terminally-ill and letting nature take its due course.
Chief Justice Misra, in a common judgment with Justice AM Khanwilkar, said it was time to "alleviate the agony of an individual" and stand by his right to a dignified passing. The five judges unanimously upheld constitutional values of liberty, dignity, autonomy and privacy.
Patients, who had appealed to the court for achieving euthanasia have also commended the decision, saying that they can die with dignity and in peace rather than facing a lifetime of suffering.
The Centre had also told the Constitution Bench that a draft bill permitting passive euthanasia with necessary safeguards was already before it for consideration. The bench stated that humans have the righ to die with dignity.
The SC had in 2017 said that the right to die in peace could not be separated from Right to Life under Article 21 of the Constitution. "For instance an elderly couple in Mumbai wrote to the Indian president recently asking for permission for active euthanasia - the concern even in this case is - are they choosing this because they have no care system in place?" Every moment our bodies undergo change... life is not disconnected from death. This decision was made as part of the verdict in a case involving Aruna Shanbaug, who had been in a Persistent Vegetative State (PVS) until her death in 2015. The guidelines included seeking a declaration from a high court, after getting clearance from a medical board and state government. State of Punjab had held both euthanasia and assisted suicide not lawful in India.
In a landmark verdict the Supreme Court allowed passive euthanasia while setting down guidelines. It added that it would also allow living will for passive euthanasia.