When presidents sign a bill into law they sometimes issue signing statements. Most of these signing statements comment on the bill or discuss the need for the bill. Additionally, they can discuss how the President interprets the language of the bill, intends to execute the bill, or gives guidance to the executive branch personnel that will execute the law.
Signing statements have been in existence since the early 19th century, and have indicated conflicts between the Executive and Legislative branches, however, they originally were rare occurrences. Since the Reagan Administration, the occurrences have become more frequent. Many administrations encouraged courts to use signing statements when interpreting the meaning of statutes, but courts have generally avoided using statements to interpret federal statutes.
Some signing statements have become controversial because presidents have used the signing statement as an opportunity to state that they will not enforce portions of a law that they consider unconstitutional. The Constitution mandates the Executive Branch, which is headed by the president, "to takes care that the laws be faithfully executed." (Article II, Section 3). This language is also known as the "Take Care Clause," and requires the President to enforce the laws passed by Congress. Traditionally, if a president does not agree with a law, either because he feels it is unconstitutional or ill-advised, he can veto it. It has also been argued that the President has taken an oath to "preserve, protect, and defend" the Constitution, and thus is required to veto a law that is unconstitutional. (Article II, Section 1). However, recent presidents have used signing statements to challenge certain provisions of a bill they signed into law, and in some cases, state that they would not enforce provisions of a bill that they find unconstitutional. The objections to provisions of laws is called the line item veto, and was ruled unconstitutional by the Supreme Court in 1998 (Clinton v. City of New York, 524 U.S. 417).
Many legal commentators, including the American Bar Association, have taken issue with the proliferation of singing statements, and the United States Congress has introduced legislation in an attempt to limit the use of Presidential Signing Statements. Singing statements are not part of the legislative process, and regardless of what is included in the signing statement, the bill, once signed, IS the law. Thus, it has been highly debated whether the signing statement is part of the legislative history. However, it is certain that signing statements give researchers insight into the executive support and enforcement a bill may receive.
For more information about Presidential Communications and Signing Statements, please take a look at these resources: