An ordinary referendum in Ireland is a referendum on a bill other than a bill to amend the Constitution. The Constitution prescribes the process in Articles 27 ("Reference of Bills to the People") and 47 ("The Referendum"). Whereas a constitutional referendum is mandatory for a constitutional amendment bill, an ordinary referendum occurs only if the bill "contains a proposal of such national importance that the will of the people thereon ought to be ascertained". This is decided at the discretion of the President, after a petition by Oireachtas members including a majority of Senators. No such petition has ever been presented, and thus no ordinary referendum has ever been held.