Procedural law or adjective law comprises the rules by which a court hears and determines what happens in civil lawsuit, criminal or administrative proceedings. The rules are designed to ensure a fair and consistent application of due process (in the U.S.) or fundamental justice (in other common law countries) to all cases that come before a court.

Substantive law, which refers to the actual claims and defenses whose validity is tested through the procedures of procedural law, is different from procedural law.

In context of procedural law; procedural rights may also refer not exhaustively to rights to Information, rights to justice, rights to participation which those rights encompassing, general Civil and Political rights. In environmental law, these procedural Rights have been reflected within the UNECE Convention on "Access to Information, Public Participation in Decision-making and Access to Justice in Environmental Matters" known as the Aarhus Convention (1998).

Legal procedure