That plastic card, the one with the lousy photo that's jammed into your wallet or purse, isn't just a license to drive. It's the green light to buy a drink, the ticket to federal benefits, the must-have document to get aboard airplanes.
Now it's also the flash point for an argument about how best to balance America's security needs with worries that personal privacy could be swept away.
The federal intelligence overhaul that became law last month - while creating a new national intelligence director and beefing up border patrols - also aims to close loopholes for identity fraud that some of the Sept. 11 terrorists used to get aboard the jets they hijacked.
Privacy advocates warn that the new federal standards for driver's licenses will effectively create a national ID card, centralizing information that can be misused - by letting the government track the whereabouts of innocent people, for instance. Government officials say they're just making the cards more secure, and that the worries are overblown.
"There is a strong sense of protection of privacy by all of the administrators of DMV records, because we know the value of the information we've been entrusted with," said George Tatum, North Carolina's Department of Motor Vehicle commissioner. "We just want you to be who you say you are."
The small provision in the massive intelligence overhaul doesn't take effect immediately. It requires a year-and-a-half of deliberation by state and federal officials, and others.
States can opt out - refuse to make changes to their driver's licenses that will be required under the federal law - but then the licenses would be useless for any federal purpose, from getting benefits to boarding an airplane guarded by federal screeners.
The intelligence law aims to standardize the documents drivers present to get a license, the ways DMV workers verify that those documents are authentic, the information included on a license and the steps authorities take to ensure licenses can't be forged. The law also requires that licenses can be read by machines.
In years past, the market for fake driver's licenses was driven by teenagers hoping to get into a nightclub or repeat drunk drivers, who lost their licenses trying to get back on the road. Now, identity theft is a bigger problem, and terrorists a bigger fear.
Many of the law's specifics have yet to be decided. Will licenses include biometric information like fingerprints or retinal scans? Will "machine-readable" mean bar codes or radio frequency identification systems - in which a tiny computer chip transmits data and can theoretically be used to track location?
Some state groups, including the National Conference of State Legislatures, opposed the proposals to have the federal government take control of what has traditionally been solely under states' control - though states have already been moving ahead to tighten the licensing process.
Advocates in Congress were given a big boost by recommendations from the Sept. 11 commission, which noted the ease with which terrorists got licenses. Still, language the House approved that would have barred driver's licenses for illegal immigrants was struck from the measure that became law. At least nine states now allow such licenses.
Civil libertarians warn that the push to make the driver's license the "gold standard" for ID will only make it easier to steal someone's identity - and will increase the value of counterfeit licenses, undermining the hopes that these steps will provide better security.
"Let's say someone steals your driver's license and substitutes their biometrics on there, and basically puts their identity on that card. They then have an official document that says they are you," said Marv Johnson at the American Civil Liberties Union. "How do you prove you are you?"
He worries, also, that personal information can be stolen or sold, or people tracked. The biggest danger is that, as the nation becomes more security-minded, and relies more on driver's licenses as ID, our society changes, Johnson said. "You just wind up being a nation where you have to show your papers to go anyplace. That's something the American people have never put up with."
The same ID across the country, even with a different logo for each of the 50 states, is "a national ID card. They might pretend it's not, but it is," said Bruce Schneier, a computer security expert and author of "Beyond Fear: Thinking Sensibly about Security in an Uncertain World."
Government officials say that the information for America's 190 million drivers is protected. Individual states maintain their own databases on driver's licenses, though all but two states allow motor vehicle administrations to share information about problem drivers through a national registry. Better technology should allow law enforcement to access more and faster data about drivers across state lines, too, said Betty Serian, deputy secretary for safety administration at Pennsylvania's Transportation Department.
Still, that doesn't mean private information will be sold, stolen or made public, Serian said and it doesn't create a central database - though Schneier would argue that point. "The information you give us right now is confidential and private," she said. "It's not in any way compromised by this new legislation."
On the Web:
American Association of Motor Vehicle Administrators: http://www.aamva.org