Executive orders are as old as the U.S. Constitution itself and usually steeped in controversy.
Every president, from George Washington to Obama, has used them. More than 13,000, in one form or another, have been issued since 1789.
While there is no specific provision in the Constitution that permits them, there is a "grant of executive power" given in Article II of the Constitution,
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Presidents have used that language, along with their constitutional powers as commander and chief over the nation's military, to issue executive orders—whether it be to change domestic policy or go to war. And they are legally binding—the U.S. Supreme Court has upheld all but two legal challenges to them (see more on that below).
Most executive orders stem from a president's desire to bypass Congress. The legislative body is not required to approve any executive order, nor can it overturn an order. The best it can do if it doesn't like an executive order is to pass a law to cut funding for the order's implementation. But even then, the president can veto such a defunding law.
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The one sure way of getting rid of an executive order is in the White House. If an administration doesn't like an order from a previous president, it can legally reverse it on its own.