Spending (budget authority and outlays) controlled in annual appropriations acts. Unlike mandatory, or non-discretionary spending, discretionary appropriations require an annual vote from a member of Congress. In 2013, only 31% of the United States federal budget was discretionary spending, the balance being entitlement, or mandatory spending, and interest on the national debt.
With discretionary spending being the only items members of Congress can control, this has led to some commentators referring to the bulk of U.S. government spending and growth of deficits as being on auto-pilot. The political philosopher and journalist George Will however, contends that all government spending is discretionary spending with the exception of debt service.