Article 21: Protection of life and personal liberty : No person shall be deprived of his life or personal liberty except according to procedure established by law.
Procedure Established by Law
It means that a law that is duly enacted by legislature or the concerned body is valid if it has followed the correct procedure.In this the court would assess that whether there is law or not, whether the Legislature is competent to frame the law and whether it had followed the procedure laid down to legislate and would not assess the intent of the said law.
Following this doctrine means that, a person can be deprived of his life or personal liberty according to the procedure established by law. So, if Parliament pass a law, then the life or personal liberty of a person can be taken off according to the provisions and procedures of the that law.