Under the Hobbs Act, the federal government has the power to prosecute someone for robbery or extortion that affects interstate commerce. And, it turns out, under the applicable law which has interpreted interstate commerce broadly, pretty much everything effects interstate commerce.
The definition is so broad that even though the government, in theory, has a duty to prove beyond a reasonable doubt that the crime affects interstate commerce, in practice, judges have held and it is the government's position, that there is no evidence that it is possible to offer that could ever show that interstate commerce is not affected by a robbery or extortion, so a defendant may not even try to offer evidence to rebut the government's claim.
So much for meaningful federalism. A case on point where a defendant tried to argue that interstate commerce wasn't affected will probably lose.
Equally troubling, and not at issue in the U.S. Supreme Court case (because the law of cruel and unusual punishment under the 8th Amendment is absurdly toothless) is that the fellow in the Hobbs act case who stole a single marijuana joint, $40 and a cell phone on one occasion (from someone assumed to be a drug dealer for purposes of appeal) and stole a single cell phone on another occasion (again, from a drug dealer), was sentenced to 20 years in prison.
The government believes that this individual was part of a larger gang that specialized in home invasion burglaries aimed at suspected drug dealers called the Goonz. But, all it had to prove beyond a reasonable doubt to the jury in order to secure the 20 year sentences was that the defendant participated in a robbery that took a single marijuana joint, $40 and a cell phone once, and a cell phone, a second time.
Maybe this was a pretty traumatic armed robbery, in which case the sentence is justified by the armed threat to persons, rather than the economic harm done. But, it sure comes across as an excessively harsh sentence for a petty crime that didn't belong in federal court as a matter of policy, whether or not the United States Constitution allows this conviction to stand.