Almost all of the federal government's actions against terrorism — from drone strikes to the prison at Guantanamo Bay — are authorized by a single law: the Authorization for Use of Military Force.
Congress passed it just after the terrorist attacks of Sept. 11, 2001. Now, President Obama says he wants to revise the law, and ultimately repeal it.
The AUMF is one of the most unusual laws Congress has passed this century. It's less than a page long. The vote was nearly unanimous. And it went from concept to law in exactly one week.
It authorizes the president to go after the groups that planned, authorized, committed or aided the Sept. 11 attacks, or any groups and countries that harbored them. In broad terms, it justified invading Afghanistan. But two presidents have applied it around the world.
"It was vast in the powers that it gave," says Karen Greenberg, who runs the Center on National Security at Fordham Law School. "And it was somewhat vast in its definition of the enemy. However, in many ways, that definition has expanded in the interim years."
Presidents Bush and Obama have used AUMF authority to kill terrorists in Somalia, Yemen and other places far from the Afghan battlefield.
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