Due process of law is the principle that the state must respect all the legal rights owed to a person, and may interfere with life, liberty or property only through fair and lawful procedures.
Origins
The idea can be traced to Clause 39 of Magna Carta (1215), which promised that no free man would be imprisoned or dispossessed except by the lawful judgment of his peers or by the law of the land. The phrase "due process of law" appears in a fourteenth-century English statute and was later entrenched in the Fifth and Fourteenth Amendments to the United States Constitution.
Procedural Due Process
Procedural due process concerns how decisions are made. Its core requirements are notice of the case against a person, a fair opportunity to be heard, an impartial decision-maker, and a reasoned decision. In criminal proceedings it includes the right to counsel, to examine witnesses and to remain silent.
Substantive Due Process
In some systems, notably the United States, due process also limits what the state may do, protecting fundamental rights from arbitrary interference even where a fair procedure is followed.
In Indonesia
The 1945 Constitution guarantees recognition, protection and fair legal certainty and equal treatment before the law (Article 28D(1)). The Code of Criminal Procedure gives effect to due process through the rights of suspects and defendants, and through pre-trial review (praperadilan) of arrests, detention and the termination of investigations.