The National Archives describes executive orders as “official documents, numbered consecutively, through which the President of the United States manages the operations of the Federal Government.” These documents are largely constitutional and uncontroversial. Despite President Obama’s relatively infrequent use of executive orders, they have become a salient topic lately, and thus warrant more explanation.
There are two relevant clauses in the U.S. Constitution regarding executive orders: Art. I Sec. 1 and Art. II Sec. 3. The first states, “All legislative Powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives.” The second clause states that the president “shall take Care that the Laws be faithfully executed.” Or, put more simply, Congress makes the laws and the president enforces the laws.
Thus, the deeply-rooted American concept of "separation of powers" is what drives the controversy of executive orders. While the president cannot "legislate," he/she must be able to control his/her branch of the government: if Congress micromanaged the executive branch, that would encroach on presidential power, and thus violate the separation of powers as much as presidential legislation would. This is the constitutional tightrope that executive orders must walk: they cannot constitute "legislation," but must allow the president to effectively run the executive branch of the government so that he/she can ensure the laws are faithfully executed.
Executive orders began as informal administrative orders, but truly took on a new role under President Franklin D. Roosevelt, who issued over 3,000 of them. In 1952 President Truman issued an executive order to seize domestic steel mills during the Korean War. This action was challenged at the Supreme Court as Youngstown Sheet & Tube Co. v. Sawyer, the first major ruling on the topic (for a more nuanced and modern case on executive orders and separation of powers, see: INS v. Chadha). In Youngstown the Supreme Court held that there was no authority for the president to issue this order under the Constitution. Essentially, because there was no law on point for the president to execute, the action of authorizing the seizing domestic steel mills constituted legislation. Since this case presidents generally cite the laws they seek to execute or enforce when issuing their executive orders to be in compliance with the Youngstown decision. It is important to note that since 9/11 the presidency has expanded in power — generally with the consent of Congress. This expansion of political and legal clout has given rise to reasonable concerns of the abuse of the executive order as a way to circumvent the legislative process.
While I am not asserting the legality of any particular executive order, I hope to have shown that the practice is one which has been exercised by every president and serves legitimate Constitutional goals. But like almost any governmental power, the possibility of abuse remains high. While we must remain wary, we must have proper historical and constitutional context, as well.