The government had defended the law as necessary to punish impostors to protect the integrity of military medals.

Continue reading

But Justices Stephen Breyer and Elena Kagan said in a separate opinion that there were ways for the government to stop liars "in less restrictive ways."

One possibility would be to "insist upon a showing that the false statement caused a specific harm or at least was material, or focus its coverage on lies most likely to be harmful or on contexts where such lies are most likely to cause harm," Breyer said.

Civil liberties groups, writers, publishers and news media outlets, including The Associated Press, told the justices they worried that the law, and especially the administration's defense of it, could lead to more attempts by government to regulate speech.

Then-Gen. George Washington established military decorations in 1782, seven years before he was elected as the first president. Washington also prescribed severe military punishment for soldiers who purported to be medal winners but weren't.

It long has been a federal crime to wear unearned medals, but mere claims of being decorated were beyond the reach of law enforcement. The Stolen Valor Act aimed to solve that problem, and won significant support in Congress during a time of war.

Alvarez's lawyers challenged the law by acknowledging their client's lies, but also insisting that they harmed no one.

"Statutes suppressing or restricting speech must be judged by the sometimes inconvenient principles of the First Amendment," Kennedy said. "By this measure, the statutory provisions under which respondent was convicted must be held invalid, and his conviction must be set aside."