1月20日，美國第46任總統喬·拜登（Joe Biden）宣誓就職後在白宮籤署文件。(© Jim Lo Scalzo/AFP/Getty Images)
President Biden signs documents after being sworn in as the 46th president on January 20 in Washington. (© Jim Lo Scalzo/AFP/Getty Images)
根據美國憲法（U.S. Constitution），美國國會(Congress)作為立法分支擁有立法權，行政分支負責實施和執行有關法律。
在某些情況下，總統也可以自行通過發布行政命令發揮立法功能，但國會對這項權力的解釋往往比總統更狹隘。
行政命令具有法律效力，有助於行政分支履行自己的責任。行政命令的授權或者來自憲法賦予總統的權力，或者來自國會在某具體法律中授予總統代行的權力。
與在一般情況下經國會通過並由總統籤署的法律一樣，行政命令也可以經法庭裁定被撤消，或被新的立法或者新的行政命令取代。
總統通常在需要採取緊急行動的情況下發布行政命令，在正式的立法程序沒有來得及完成時提供指令。美國歷史上最著名的行政命令之一是亞伯拉罕•林肯（Abraham Lincoln）總統1863年發布的解放宣言（Emancipation Proclamation）。
On his first day in office, President Biden issued 17 executive actions addressing his administration’s most urgent policy priorities.
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.
This article was originally published December 16, 2014.
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