In the case of Billy Joe Reynolds v. United States (2011), the Supreme Court ruled on whether a registered sex offender who failed to update his registration after traveling between states could be prosecuted under federal law, even if he was not informed about this requirement. The court held that ignorance of the law is no defense and upheld Reynolds' conviction. This decision clarified that under the Sex Offender Registration and Notification Act (SORNA), offenders are required to register in each jurisdiction where they live, work or study, regardless of whether they have been informed about these requirements by authorities.

In the dissenting opinion for Billy Joe Reynolds v. United States, Justice Breyer argued that the majority's interpretation of federal law was too broad and could lead to unjust outcomes. He contended that the requirement for sex offenders to register before leaving their state of residence should only apply if they were already required to register under SORNA at the time they traveled across state lines. According to him, this would not have been possible in Reynolds' case as he moved interstate before SORNA was enacted and therefore couldn't have registered beforehand. Breyer also expressed concern about potential due process violations arising from imposing criminal penalties on individuals who may not be aware of their legal obligations under a new law like SORNA without proper notification or guidance from authorities.