What legal principle governs who can file a lawsuit?

The principle that governs who is able to file a lawsuit is known as standing. Standing is a legal concept that ensures a party has a sufficient connection to and harm from the law or action challenged to support their participation in the case. In other words, for a plaintiff to bring a lawsuit, they must demonstrate that they have suffered an actual injury or have a direct stake in the outcome of the case. This requirement helps to ensure that courts only address genuine disputes where there is a legitimate and personal interest at stake, preserving judicial resources and focusing the court's attention on real controversies.

Other concepts mentioned, such as judicial review, common law, and due process, while fundamental to the legal system, do not specifically address the criteria for who is allowed to initiate legal proceedings. Judicial review relates to the courts' power to assess the constitutionality of legislative and executive actions; common law refers to law developed through court decisions rather than statutes; and due process pertains to the legal requirement that the state must respect all legal rights owed to a person. Each of these plays a critical role in the judicial system, but they do not define the parameters of standing in the context of filing a lawsuit.