William Blackstone cites the first recorded usage of "habeas corpus ad subjiciendum" in 1305, during the reign of King Edward I. However, other writs were issued with the same effect as early as the reign of Henry II in the 12th century. Blackstone explained the basis of the writ, saying "he king is at all times entitled to have an account, why the liberty of any of his subjects is restrained, wherever that restraint may be inflicted." The procedure for issuing a writ of "habeas corpus" was first codified by the Habeas Corpus Act 1679, following judicial rulings which had restricted the effectiveness of the writ. A previous law (the Habeas Corpus Act 1640) had been passed forty years earlier to overturn a ruling that the command of the King was a sufficient answer to a petition of "habeas corpus". The cornerstone purpose of the "writ of habeas corpus" was to limit the King's Chancery's ability to undermine the surety of law by allowing courts of justice decisions to be overturned in favor and application of "equity", a process managed by the Chancellor (a bishop) with the King's authority.