The Constitution, of course, doesn't define legislative power but there were certain background understandings and background sources of law that the Founders all accepted with respect to the definition of legislative power. One important source for the Founders was John Locke who explained, who argued that the legislative power was the power to make standing, general, and prospective rules for the government of society. The rules governing private individual conduct. Just with this definition, the legislative power could extend to all subjects and all objects. But the Constitution, in Article 1, does not grant a plenary legislative power to Congress. Article 1, Section 1, says all legislative power herein granted shall be vested in a Congress of the United States of America. Thus, Congress, the national government, only has legislative power, the power to make rules for the government of society only with respect to a certain limited number of enumerated objects. The objects enumerated in Article 1, Section 8 of the Constitution. Having said that, Congress's power was also expanded in certain ways. It was expanded when the Framers enumerated certain powers and gave it to Congress even though those powers had historically been executive powers or prerogative powers. For example, Congress has the power to declare war, Congress has the power to issue letters of marque and reprisal, Congress has the power to coin money. Historically, these were prerogative powers that belonged to the British King.