The correct answer is Procedure established by Law.

• Article 21. Protection of life and personal liberty.
  • No person shall be deprived of his life or personal liberty except according to the procedure established by law.

• Due process of law = Procedure established by law + Fairness of that procedures.
• Procedure established by law - It ascertains the validity of legislation by checking that whether the legislation in question is duly enacted or not.
• Due process of law - It ascertains the validity of law by checking both the procedural and substantial aspects of law i.e. whether or not the law is fair, just, and equitable.
• The scope of judicial review power of the Supreme Court in India is narrower than that of what exists in the US.
• This is because the American Constitution provides for ‘due process of law.
• ​‘Rule of Law’ as embodied in Article 14 is a ‘basic feature’ of the constitution.
• Concept of ‘Rule of Law’, propounded by A.V. Dicey, the British jurist.
• His concept has the following three elements or aspects: 
  • Absence of arbitrary power, that is, no man can be punished except for a breach of law.
  • Equality before the law is equal subjection of all citizens to the ordinary law of the land administered by the ordinary law courts.
  • The primacy of the rights of the individual,
    • That is, the constitution is the result of the rights of the individual as defined and enforced by the courts of law rather than the constitution being the source of the individual rights.