The rule of law requires that the executive in its coercive action be bound by rules which prescribe not only when and where it may use coercion but also in what manner it may do so. The only way in which this can be ensured is to make all its actions of this kind subject to judicial review.
—Friedrich Hayek. The Constitution of Liberty, 1960.
The judiciary exercises oversight of the executive branch through judicial review of administrative decisions. Judicial review involves the court determining whether the government’s action is authorized by legislation and not prohibited by the constitution. For this process to be effective, legislation must be drafted so as not to grant excessive discretion to the executive.
The writ of habeas corpus
The Habeas Corpus Acts declare no principle and define no rights, but they are for practical purposes worth a hundred constitutional articles guaranteeing individual liberty.
—Albert Dicey. An Introduction to the Study of the Law of the Constitution, 1885.
The writ of habeas corpus is a court order requiring a prisoner to appear before the court to determine whether he is being held lawfully. If the jailer is unable to establish the legal basis for the imprisonment, then the prisoner walks free. It follows that the only people who should fear, resist, or purport to suspend habeas corpus are those who wish to continue unlawfully imprisoning someone. Habeas corpus is thus simply a mechanism for enforcing due process.
The writ of habeas corpus should never be suspended. In dire emergencies, those apprehended should be charged with rioting, looting, breaking curfew, etc. If there is no specific charge, then they ought not be detained. Even when police officers cannot be spared to give evidence, their video-recorded testimony should suffice to warrant the continued detention of law-breakers. If there are not enough judges to hear applications for writs, or if the courts have been disrupted, that does not mean the writ should be suspended, it simply means applications cannot immediately be heard.
The writ of mandamus
The writ of mandamus is a court order requiring that a public official carry out an act legally required of that official. The writ of mandamus orders an official to take a positive action.
The writ of mandamus, like the requirement for due process and like the writ of habeas corpus, supports the rule of law by insisting that officials do not act as a law unto themselves. Instead it requires that officials follow the exact letter of the law, neither doing what it does not authorize nor neglecting to do what the law requires them to do.
Wherever a government official is required to make a decision concerning the rights of a member of the public, the official must explain his reasons. Those reasons must be sufficient to allow a court to review the propriety of the exercise of discretion.