Article One of the United States Constitution
This clause is known as the Presentment Clause. Before a bill becomes law, it must be presented to the President, who has ten days (excluding Sundays) to act upon it. If the President signs the bill, it becomes law. If he disapproves of the bill, he must return it to the House in which it originated together with his objections. This procedure has become known as the veto, although that particular word does not appear in the text of Article One. The bill does not then become law unless both Houses, by two-thirds votes, override the veto. If the President neither signs nor returns the bill within the ten-day limit, the bill becomes law, unless the Congress has adjourned in the meantime, thereby preventing the President from returning the bill to the House in which it originated. In the latter case, the President, by taking no action on the bill towards the end of a session, exercises a "pocket veto", which Congress may not override. In the former case, where the President allows a bill to become law unsigned, there is no common name for the practice, but recent scholarship has termed it a "default enactment."