From left, Medals of Honor for the Army, Air Force and Navy. (Congressional Medal of Honor Society/CONGRESSIONAL MEDAL OF HONOR SOCIETY)

Xavier Alvarez will soon have something to brag about, assuming anyone believes him. On Wednesday, he will join the small number of citizens who have appeared before the U.S. Supreme Court. He has secured this distinction, however, not by what he achieved in his life but what he falsely claimed to have achieved.

Alvarez, you see, is a liar. Upon that much, everyone agrees. What has perplexed judges is whether his lies are protected by the First Amendment.

In the annals of deceit, Alvarez is something of a standout. After his election to a water board in California, he introduced himself at a public meeting as “a retired Marine of 25 years,” a repeatedly wounded warrior and a Medal of Honor recipient. He also told people that he was once a professional hockey player with the Detroit Red Wings and was secretly married to a Mexican starlet. A few people thought it curious that a former hockey star and war hero ended up on the Three Valleys Municipal Water District board in Claremont, Calif., so far from his starlet wife. It seemed like virtually everything he said about himself after “I am Xavier Alvarez” wasn’t true. He was found out, publicly ridiculed and hounded out of office.

Normally, that would be the end of it. However, for local prosecutors, it was not enough to expose Alvarez as a fraud — they decided to make him one of the first people prosecuted under the Stolen Valor Act of 2005. Signed into law by President George W. Bush, the act makes it a crime to falsely claim “to have been awarded any decoration or medal authorized by Congress for the Armed Forces of the United States.” Across the country, a number of rather pathetic individuals are being prosecuted for parading around in uniforms and pretending to be heroes.

The problem with the law they may have broken is not just that it is unnecessary, but that it can be dangerous to criminalize lies. After all, with the power to punish a lie comes the power to define the truth — a risky occupation for any government.

After Alvarez was convicted, he challenged the constitutionality of the law, claiming that it violated his First Amendment rights. The federal court of appeals in San Francisco ruled in his favor in two separate opinions. Now the case will go to the Supreme Court, where the Obama administration will argue that the First Amendment does not protect lies as it does true statements.

Under this logic, Congress would be able to criminalize statements solely because they are lies, alleging some type of amorphous social harm. The government would become the truth police, determining when fibs become felonies.

Lying about military service is a long and dishonorable tradition, standard since the founding of the republic. Some of our greatest colonial heroes were accused of lying about their military records. Gen. Friedrich Wilhelm von Steuben, who served in the Continental Army during the American Revolution, passed himself off as a “lieutenant general in the king of Prussia’s service” when it appears that he not only had been discharged under a cloud of controversy from the King of Prussia’s service but had achieved only the rank of captain.

The Stolen Valor Act criminalizes what many view as a common human impulse. When the issue was raised before the federal appeals court, Chief Judge Alex Kozinski balked at the notion that lies can be crimes in a society saturated by untruths. “Saints,” he noted, “may always tell the truth, but for mortals living means lying.” Kozinski is supported by a host of studies on the human propensity, even necessity, to lie. This tendency to shape the truth can combine with a certain human inclination toward fantasy.

While common, lies have limits. The dividing line in the law has always been fraud or related crimes — using lies to gain money or benefits. When someone lies about their military service or makes other claims, such as an incurable illness, to enrich themselves, it is a crime. It is not the lie but the larceny that is being prosecuted. But the Stolen Valor Act was designed to address cases in which the individual is not deriving financial gain or other benefits; rather, the law punishes the boast or the brag itself.

Faux warriors tend to be liars who take the added step of merging their fantasy lives with their actual lives. Darrow “Duke” Tully, once a close associate of Sen. John McCain, often discussed his harrowing moments as a combat pilot with 100missions over Vietnam and told of surviving the crash of a fighter jet in Korea. It turned out that he did not receive the Purple Heart, the Distinguished Flying Cross or the Vietnam Cross of Gallantry — he was never even in the military. For Tully, the penalty was public shame and the loss of the respect he had enjoyed as the publisher of the Arizona Republic.

The people who take their fantasies to the extreme of wearing uniforms and medals are few, and they are usually easy to spot. When Michael Patrick McManus walked into a party for Houston Mayor Annise Parker in 2010, he was covered in military medals, including paratrooper jump wings and a chivalric medallion indicating that he was a Commander of the British Empire.

For these individuals, the desire to self-promote is often irresistible and eventually insatiable — even when they take things to absurd levels. When former Marine Staff Sgt. David Weber promoted himself to a two-star major general with two Purple Hearts, he was quickly uncovered by someone who simply looked at the relatively short list of generals. Likewise, Illinois judge Michael F. O’Brien was exposed after he sought special license plates to go along with the Medal of Honor he claimed to have earned. He was denounced and forced off the bench.

Steve Burton, a bank employee from Palm Springs, Calif., was uncovered at his high school reunion in 2009 when he appeared in the uniform of a Marine lieutenant colonel decorated with an array of medals, including the Purple Heart, the Bronze Star and the Navy Cross. All were recognitions, he claimed, from a grateful nation for his service in Afghanistan and Iraq. Unfortunately for him, he ran into a former classmate who was a real Navy commander and who exposed him as a fraud.

These stories, and the public ridicule that comes with the make-believe, show that we have little tolerance for fake heroes and ample means to detect them. The Stolen Valor Act merely adds a criminal charge to public scorn.

Supporters of the bill insist that prosecutions are needed to maintain the value and dignity of our military citations. The Congressional Medal of Honor Foundation has taken this argument one step further in its amicus brief to the Supreme Court. It says these medals are not just recognitions of heroism but the very inducement for heroism. It chastised the federal court for its “lack of appreciation” when the court said it was insulting to suggest that heroes are motivated by the desire for medals, and it insisted that heroes do seek these medals in risking their lives.

Putting aside the question of whether these frauds discourage real heroism, the implications for free speech are chilling. If the government can criminalize lies about medals, it can criminalize lies about other subjects. If it is harmful to lie about soldiers, what about lying about being a former police officer or a former firefighter? How about lying about politicians or religion or terrorism?

Once we criminalize lies, someone must determine what is a lie and what is harmless embellishment. One person who appears comfortable with that role is Judge Jay Bybee, who wrote one of the dissenting opinions in the Alvarez case. Bybee, who was an assistant attorney general in the Justice Department’s Office of Legal Counsel under President George W. Bush, is one of the authors of the Bush administration’s infamous “torture memos.” These memos justified the use of waterboarding and were later retracted by the Bush administration as “flawed.” Bybee was accused of misrepresenting legal authority to justify what many view as not just a torture program but a war crime. That form of falsehood, however, appears protected — the Justice Department didn’t even report Bybee to his bar association.

In my view, misrepresenting legal authority to defend torture is far more damaging to the nation than someone prancing around with a Silver Star and some French Foreign Legion medallion.

The First Amendment protects free speech, not just truthful speech. It exists to give a certain breathing room to citizens to avoid the chilling effect of the threat of prosecution. Free speech is its own disinfectant. It tends to expose lies and isolate liars. But it means that we often protect speech that has little value in its own right. We are really not protecting the right of Xavier Alvarez to tell lies. We are protecting the right of everyone to speak, even when they may be called liars.

As for our heroes, they are no more diminished by pathetic pretenders than top singers are diminished by bad karoke. We know the real thing when we see it.

Jonathan Turley is the Shapiro professor of public interest law at George Washington University.

Read more from Jonathan Turley in Outlook:

— “10 reasons the U.S. is no longer the land of the free

— “Supreme Court’s GPS case asks: How much privacy do we expect?

— “Separation of church and state? Not on the 2012 campaign trail