On his third day in office, President Obama issued an executive order banning certain interrogation techniques used by the CIA after the 9/11 attacks. What is an executive order?

Under the U.S. Constitution, the legislative branch (Congress) has the power to enact laws. The executive branch is charged with implementing and enforcing those laws.

Sometimes the president can function as a lawmaker in his own right by issuing an executive order, although Congress usually interprets that authority more narrowly than the president.

Executive orders are issued to help the executive branch carry out its duties, and they have the force of law. An order’s authority comes either from a power granted to the president by the Constitution or from power delegated to the president by Congress in a specific law.

Just like laws passed in the usual way — enacted by Congress and signed by the president — executive orders can be reviewed by the courts and can be struck down. They can also be overwritten by new legislation or new executive orders.

Executive orders are useful when action is urgently needed, and can provide direction until the formal lawmaking process catches up. One of the most famous executive orders in U.S. history was President Abraham Lincoln’s 1863 Emancipation Proclamation.

During his first six years in office, President Obama has issued 194 executive orders. George W. Bush issued 291 and Bill Clinton issued 364 during their terms.