This part of the “Commerce Clause,” which gives Congress the authority to regulate foreign and interstate commerce, is the basis for most federal law regulating economic activity.

Prior to the New Deal, this clause was often cited by courts that struck down state laws that favored local businesses over out-of-state competitors.

But since the 1930s, the courts have relied on this clause primarily to uphold federal regulation of economic activity.

Interstate commerce has been defined very broadly – therefore, the authority of Congress under the Commerce Clause is very broad. For example, in 2005 the Supreme Court upheld a federal law criminalizing the production and use of home-grown medical marijuana. One of the dissenters in that case questioned how an individual’s cultivation and personal consumption of marijuana could be considered “Commerce … among the several states.” Gonzales v. Raich, 545 U.S. 1 (2005).