What is Interstate Commerce Commission?

Legal Definition
The Interstate Commerce Commission (ICC) was a regulatory agency in the United States created by the Interstate Commerce Act of 1887. The agency's original purpose was to regulate railroads (and later trucking) to ensure fair rates, to eliminate rate discrimination, and to regulate other aspects of common carriers, including interstate bus lines and telephone companies. Congress expanded ICC authority to regulate other modes of commerce beginning in 1906. The agency was abolished in 1995, and its remaining functions were transferred to the Surface Transportation Board.

The Commission's five members were appointed by the President with the consent of the United States Senate. This was the first independent agency (or so-called Fourth Branch).
-- Wikipedia
Legal Definition
A commission created by the interstate commerce act (q. v.) to carry out the measures therein enacted, composed of five persons, appointed by the President, empowered to inquire into the business of the carriers affected, to enforce the law, to receive, investigate, and determine complaints made to them of any violation of the act, make annual reports, hold stated sessions, etc.
-- Black's Law Dictionary
Legal Definition
A board of five appointed by the President and confirmed by the Senate under the Interstate Commerce Act to carry out the provisions thereof.
-- Ballentine's Law Dictionary