A (proposed) formal act (or "law") of a legislative body (such as the U.S. Congress or a state legislature) that legally establishes a new government agency or programme or else renews or extends an existing agency or programme whose previous legal authorization to exist would otherwise expire with the passage of time. Authorizations may be for one year or more than one year — about one-half of current Federal spending is by agencies or programmes subject to annual re-authorization, while the other half gets its legal basis either from longer term authorization bills or from permanent laws that provide spending authority automatically to ongoing entitlement programmes like Social Security. Authorization bills also include specific figures as funding levels for the agencies and programs, but these sums are upper limits only (for the guidance of the appropriations committee) — no money can actually be spent or committed by the agency or programme administrators until after a separate appropriation bill has also been passed and signed into law, legally enabling the Treasury to disburse the money. The amount of money eventually appropriated for an agency or programme is most often less than the amount previously authorized, so an authorization bill is rather like a necessary "hunting license" for an appropriation rather than a guarantee. No appropriation can be made for an unauthorised program, but even an authorised programme may still die or be unable to perform all its assigned functions for lack of a sufficiently large appropriation of funds. This often happens in the decentralised American political system, because authorization bills are each drafted by one of the many specialised standing committees in Congress (the Agriculture Committee, the Armed Forces Committee, etc. — who tend to be cheerleaders for "their" pet agencies), while appropriation bills are drafted by the different set of lawmakers who serve on the specialised subcommittees of the Appropriations committees in the two chambers (who still have to get their funding choices through the full Appropriations committee, which is responsible for weighing the relative merits and urgency of all the different programmes against each other before dividing up the budget pie).