The common law courts thus used the writ of habeas corpus to protect, assert and extend their own jurisdiction against the various rival courts by securing the release of litigants and others from custody. By means of this writ they brought before themselves and released persons who had been imprisoned by one of the rival courts if, in their opinion, the Court had acted in excess of its jurisdiction. The writ of habeas corpus, known in this form as habeas corpus ad subjiciendum, thus came to be a writ by which a person unlawfully imprisoned could secure his release. In this way it assumed great constitutional importance as a device for impugning the validity of arbitrary imprisonment by the executive and, as pointed out by Holdsworth in vol.I of his "History of English Law”, “its position as the most efficient protector of the liberty of the subject was unquestioned after the Great Rebellion". It was for this reason that men began to assign as its direct ancestor the clauses of the Magna Carta which prohibited imprisonment without due process of law. The history of the writ which we have given shows that there is no direct descent but there can be no doubt that there is an indirect connection between the writ and the Magna Carta, because, far more effectively than any other remedy, the writ helped to vindicate the right of freedom guaranteed by the famous words of the Magna Carta. The decision in Darnel's case((1627) 3 ST 1) was a set-back in the struggle for liberty since it eroded to some extent the effectiveness of the writ by taking the view that a return that the arrest was "by the special command of the King" was a good and sufficient return to the writ, which meant that a lawful cause of imprisonment was shown. But the Petition of Right, 1627 overruled this decision by declaring such a case of imprisonment to be unlawful. In the same way, it was enacted in the Habeas Corpus Act, 1640 abolishing the Star Chamber that any person committed or imprisoned by order of the Star Chamber or similar bodies or by the command of the King or of the Council should have his habeas corpus. There were various other defects also which were revealed in course of time and with a view to remedying those defects and making the writ more efficient as an instrument of securing the liberty of the subject unlawfully detained, reforms were introduced by the Habeas Corpus Act, 1679, and when even these reforms were found insufficient, the Habeas Corpus Act, 1816 was enacted by which the benefit of the provisions of the Habeas Corpus Act, 1679 was made available in cases of civil detention and the judges were empowered to inquire into the truth of the facts set out in the return to the writ. The machinery of the writ was thus perfected by legislation and it became one of the most important safeguards of the liberty of the subject and, as pointed out by Lord Halsbury L.C., in Cox v. Hakes, ((1890) 15 AC 506) it has throughout "been jealously maintained by courts of law as a check upon the illegal usurpation of power by the executive at the cost of the liege”.
