While bicameral legislatures such as the Congress of the United States allow bills to originate in both chambers, Austrian federal legislation always originates in the National Council, never in the Federal Council. In theory, bills can be sponsored by National Council members, by the federal cabinet, by popular initiative, or through a motion supported by at least one-third of the members of the Federal Council. In practice, most bills are proposed by the cabinet and passed after mere token debate. Bills passed by the National Council are sent to the Federal Council for affirmation. If the Federal Council approves of the bill or simply does nothing for a period of eight weeks, the bill has succeeded. Bills passed by both houses (or passed by the National Council and ignored by the Federal Council) are ultimately signed into law by the federal president. The president does not have the power to veto bills, his or her signature is a technical formality notarizing that the bill has been introduced and resolved upon in accordance to the procedure stipulated by the constitution. The president does not even have the authority to refuse signing a bill he or she deems unconstitutional as such; a bill may be vetoed only on the grounds that its genesis, not its substance, is in violation of basic law. Adjudicating upon the constitutionality of the bill itself is the exclusive prerogative of the Constitutional Court.