James Wilson said during the Philadelphia Convention in 1787 that, "Laws may be unjust, may be unwise, may be dangerous, may be destructive; and yet not be so unconstitutional as to justify the Judges in refusing to give them effect." George Mason agreed that judges "could declare an unconstitutional law void. But with regard to every law, however unjust, oppressive or pernicious, which did not come plainly under this description, they would be under the necessity as judges to give it a free course." Chief Justice John Marshall (joined by Justice Joseph Story) took a similar position in 1827: "When its existence as law is denied, that existence cannot be proved by showing what are the qualities of a law."