Martha Stewart’s conviction has drawn attention to the obscure federal law that makes it a crime to lie to investigators. Until Stewart’s high-profile prosecution, most people were under the mistaken impression that it is only a crime to lie under oath. Legal experts are now saying it is too risky for citizens to speak with investigators. The New York Times quotes white-collar defense lawyer Seth Taube: ”You have an absolute right in this republic not to talk to the government.” Only one problem: That may no longer be the case.

Most people, including lawyers, are under the impression that when Americans are confronted with law enforcement agents, they have the right to remain silent. We’ve all heard it on television hundreds of times. However, prosecutors in Nevada challenge that proposition in a case pending before the U.S. Supreme Court, Hiibel vs. Sixth Judicial District. The case involves a man who was prosecuted for refusing to speak with a police officer. In coverage of the high court, this case has been overshadowed by high-profile terrorism cases and the release of Justice Harry Blackmun’s personal papers. But Hiibel may prove to be the sleeper case of the term because of its profound implications.

Nevada rancher Dudley Hiibel was standing outside his truck smoking a cigarette when a police officer approached and demanded to see some identification. Hiibel was taken aback by the demand and began to respond to the deputy’s questions with his own questions. When the deputy said, ”Do you have identification on you?” Hiibel replied, ”Why?” After a brief verbal tussle, Hiibel announced, ”I don’t wanna talk.” The officer put him in handcuffs and took him to jail. Hiibel was charged with ”obstructing an officer” and was fined $250. Hiibel’s lawyers have challenged the constitutionality of this charge all the way to the U.S. Supreme Court, which will hear arguments in the case today.

Of course, the cop who confronted Hiibel was not just looking to hassle people in town that day. The officer was responding to a 911 call by someone who claimed to have seen a man strike a woman inside a pickup truck. It was perfectly appropriate for the policeman to check things out. But for some reason, the deputy seemed fixated on getting Hiibel to surrender his name and some official ID when he could have taken other steps to gather information.

The officer could have called in the license plate number of Hiibel’s truck or tried to speak with the woman sitting in the truck (who turned out to be Hiibel’s 17-year-old daughter). Nevada law requires citizens to identify themselves whenever a police officer has ”reasonable suspicion” to believe that a crime has occurred or is about to occur. The Supreme Court is thus confronted with the question of whether an American should be jailed for keeping his mouth shut — for respectfully saying, ”I don’t wanna talk.”

Some people may shrug and say, ”What’s all the fuss? It’s only your name.” There are at least three responses to that. First, it would be naive for anyone to think that government will stop with a simple ”name loophole” to the right to remain silent. If the Supreme Court upholds Hiibel’s conviction, it will simply generate more litigation over the amount of information that can be compelled from a person’s own mouth. And remember that saying the wrong thing — even just denying wrongdoing — can lead to an indictment for ”misleading an investigator.”

Second, the case has implications for national ID card schemes that have been proposed since the 9/11 terrorist attacks. Countries around the world that have national ID cards require the cards to be carried in public, and it is a crime to refuse to produce it when a government agent demands it. The Justice Department has intervened in this case to argue that identification requirements comport with the Constitution. If the Nevada law is upheld, a precedent will have been established for a national law.

Third, and most fundamentally, a crucial principle is at stake. Unlike so many other countries, Americans can criticize government officials — from president on down to the local patrolman. The logical corollary to that is that Americans can also exercise the right not to speak to government officials. We must insist that the police do their job while honoring the individual’s choice to speak or not to speak.

Circumstances do matter, of course. Hiibel was not trying to get into the White House without identifying himself, for example. He was standing along a public highway and he said, ”I don’t wanna talk.” For that, he was arrested. But can it really be a crime in America to stand in public peacefully and quietly? Stay tuned. A Supreme Court ruling in the case is expected by summer.