The U.S. government claims the right to eavesdrop at will on a citizen's email if he or she is writing to someone who lives abroad. Now it wants to be able to use those emails to convict the person sending them of a crime.
That's what's happening to Aws Mohammed Younis al-Jayab — and he's not the only one. The legal basis is the 2008 Amendment Act to the Foreign Intelligence Surveillance Act, which says the government may monitor communications from within the U.S. to foreigners abroad, or vice versa, without first obtaining a warrant to authorize the surveillance.
No court has yet reviewed the law's constitutionality because until 2013 the government didn't tell anyone that it had been doing this. The Supreme Court ruled in 2013 that no one had legal standing to challenge the law based merely on the speculation that it might be applied to them.