A federal law that makes it illegal to lie about being a military hero with medals should be upheld because it doesn't target legitimate free speech, prosecutors told an appeals court.

The U.S. attorney for Colorado asked the 10th U.S. Circuit Court of Appeals in Denver late Monday to overturn a lower court ruling that the Stolen Valor Act violates the First Amendment.

The law, passed by Congress in 2006, makes it a crime punishable by up to a year in jail to falsely claim to have received a medal from the U.S. military.

It is also being challenged in a separate case in California. Some legal scholars have said they expect the law to eventually land before the Supreme Court.

In the Colorado case, Rick Glen Strandlof, who founded a veterans group in Colorado Springs, was charged in 2009 with violating the law by claiming to be an ex-Marine who was wounded in Iraq and received the Purple Heart and Silver Star. The military said it had no record that he ever served.

A federal judge threw out the case in July, ruling the U.S. government had not shown any compelling reason to restrict that particular type of speech.

The judge also ruled that lying about getting a military medal doesn't fall into any of the limited exceptions to free speech that the Supreme Court has recognized, including fraud.

In a written brief filed Monday to support their appeal, prosecutors said the law does serve a compelling government need, protecting the integrity and value of medals that recognize extraordinary service.

The law also aims to keep impostors from wrongly getting the benefits, reputation and credibility meant for legitimate heroes, prosecutors wrote.

The law doesn't require a showing that an alleged impostor got financial benefits or caused financial harm for a conviction.

The appeals court hasn't said whether it will hear oral arguments or make a ruling based only on written briefs. Strandlof's lawyer didn't immediately return a telephone message Tuesday.

In the California case, Xavier Alvarez, a water board official from Pomona, was indicted in 2007 after saying at a public forum that he was a retired Marine who received the Medal of Honor, the nation's highest military decoration.

He pleaded guilty on condition that he be allowed to appeal on First Amendment grounds. A three-judge panel of the 9th Circuit ruled 2-1 in his favor in August.

In September, government attorneys asked the full appeals court to reconsider, saying the case raises "exceptionally important" questions about the First Amendment.

The court hasn't indicated whether it will grant the request.