The “knowingly” element of the federal gun law that prohibits certain people – such as aliens and those convicted of felonies – from possessing firearms requires the Government to prove that a defendant both knew he possessed the firearm and knew of his relevant status when he possessed it, the U.S. Supreme Court held June 20 in Rehaif v. United States.
18 U.S.C. §922(g) provides that “it shall be unlawful” for certain people to possess firearms.  §924(a)(2) provides that anyone who “knowingly violates” the provision shall be fined or imprisoned for up to 10 years.
Hamid Rehaif entered the U.S. on a student visa, which was later terminated after he dropped out of school.
He later went to a firing range and shot two firearms. 
The Government prosecuted him for possessing firearms as an unlawful alien.
Rehaif argued that the trial court erred in instructing the jury that it did not need to find that he knew he was in the country unlawfully.
The Court, in a 7-2 opinion, agreed. 
The term “knowingly” applies both to the defendant’s conduct (possessing the firearm) and his status (being an unlawful alien), the Court held.
 “Whether a criminal statute requires the Government to prove that the defendant acted knowingly is a question of congressional intent,” the Court said.  “We start from the longstanding presumption, traceable to the common law, that Congress intends to require a defendant to possess a culpable mental state regarding each of the statutory elements that criminalize otherwise innocent conduct.”
 “We apply the presumption in favor of scienter even when Congress does not specify any scienter in the statutory text,” the Court said.  “But the presumption applies with equal or greater force when Congress includes a general scienter provision in the statute itself.”
Scienter requirements advance the “basic principle of criminal law by helping to separate those who understand the wrongful nature of their act from those who do not,” the Court said.
 “We have typically declined to apply the presumption in favor of scienter in cases involving statutory provisions that form part of a ‘regulatory’ or ‘public welfare’ program and carry only minor penalties,” the Court said.  That’s not the case here because the statute carries a penalty of up to 10 years in prison.
Dissenting opinion
Justice Alito, joined by Justice Thomas, dissented. 
They said the Court was “casually” overturning 30 years of precedent interpreting the statute differently.
They said the ruling “opens the gates to a flood of litigation” from prisoners currently serving time under the statute who may now have an avenue to challenge their convictions.