But the writ of habeas corpus had existed in various forms in England for at least five centuries before and is thought to have originated in the Assize of Clarendon of 1166.

[5] In criminal matters other than treason and felonies (a distinction which no longer exists), the act gave prisoners or third parties acting on their behalf the right to challenge their detention by demanding from the Lord Chancellor, Justices of the King's Bench, and the Barons of the Exchequer of the jurisdiction a judicial review of their imprisonment.

[6][7] The Act came about because the Earl of Shaftesbury encouraged his friends in the Commons to introduce the Bill where it passed and was then sent up to the House of Lords.

[8] However, the Commons had no choice but to pass the Bill with the Lords' amendments because they learned that the King would soon end the current parliamentary session and they desired to see the Act enacted, even with limitations.

A popular but likely untrue anecdote holds claims that the Act only passed because the votes in favour were miscounted as a joke.

[9] King Charles II assented to the Act in 1679 since, Nutting explains, "it was no longer controversial".