<Li> First, Congress may regulate the use of the channels of interstate commerce; </Li> <Li> Second, Congress is empowered to regulate and protect the instrumentalities of interstate commerce, or persons or things in Interstate Commerce, even though the threat may come only from intrastate activities; </Li> <Li> Finally, Congress's commerce authority includes the power to regulate those activities having a substantial relation to interstate commerce (i.e., those activities that substantially affect interstate commerce). </Li> <P> Thus the federal government did not have the power to regulate relatively unrelated things such as the possession of firearms near schools, as in Lopez . This was the first time in sixty years, since the conflict with President Roosevelt in 1936--37, that the Court had overturned a putative regulation on interstate commerce because it exceeded Congress's commerce power . Justice Clarence Thomas, in a separate concurring opinion, argued that allowing Congress to regulate intrastate, noncommercial activity under the Commerce Clause would confer on Congress a general "police power" over the entire nation . </P>

The commerce clause of the u.s. constitution authorizes