When the Constitution was written, one of the key decision was to divide the powers of government among several branches with the goal of making tyranny difficult. Thus, the power to legislate was given only to Congress under Article 1, while the power to execute the laws was given only to the executive branch controlled by the Office of the President, under Article 2. In addition, after Marbury v. Madison (1803), the Supreme Court holds the power to determine if either branch has acted unconstitutionally.
The Constitution also creates some sharing of powers. For example, while a president may not make law, the president may veto laws under Article 1, Section 7.
For more on how the separation of powers has and has not limited the presidency, see our short course:
The Presidency – a seven part course« Back to Glossary Index