Under the federal Sex Offender Registration and Notification Act (SORNA), sex offenders must register as sex offenders and update their registration when they travel from one state to another. David Hall, a convicted sex offender in New York, moved from New York to Virginia, lived there for part of a year, and then returned to New York. When he returned, he was charged with the federal offense of failing to register as a sex offender while in Virginia, as required by SORNA. In his defense, he claimed that SORNA was unconstitutional because Congress had no authority to criminalize interstate travel where no commerce was involved. The federal district court dismissed the indictment. The government appealed, contending that the statute is valid under the commerce clause. Does that contention seem reasonable? Why or why not? [United States v. Hall, 591 F.3d 83 (2d Cir. 2010)]