Signing statements are used by Presidents to comment on signed bills being enacted into laws. Comments can include the President's interpretation of the law's language; objections to provisions of the law; and the President's intent regarding the execution of the law, giving guidance to executive branch agencies.
See the Library of Congress guide on Presidential Signing Statements for an in-depth discussion.
Signing statements are available in Presidential Documents. The are also generally published in the Congressional Record and as House Documents, both of which are available in Proquest Congressional.