What is Legislative Power?

Legal Definition
The power of congress to make laws. Additionally, as an incident to that power, congress can conduct hearings and investigations, consider those matters that form the basis on which Congress may enact legislation, and perform other duties that are "necessary and proper" to the enacting legislation pursuant to Article I, Section I.

See Congressional power.
Legal Definition
The lawmaking power; the department of government whose function is the framing and enactment of laws. Evansville v. State, 118 Ind. 426, 21 N. E. 267, 4 L. R. A. 93; Sanders v. Cabaniss, 43 Ala. 180; Brown v. Galveston, 97 Tex. 1, 75 S. W. 495; O'Neil v. American F. Ins. Co., 166 Pa. 72, 30 AtL 943, 26 In R. A. 715, 45 Am. St Rep. 650.
-- Black's Law Dictionary
Legal Definition
The power to make, alter or repeal laws. See 166 Pa. St. 72, 45 Am. St. Rep. 650, 26 L. R. A. 715, 30 Atl. 943, 945.
-- Ballentine's Law Dictionary
Legal Definition
The authority under the constitution to make laws and to alter or repeal them.
-- Bouviers Law Dictionary