Is the relative anonymity the open road has long afforded something we're ready to give up? In an up or down vote, I'm confident the American people would say, "Hell no." But automatic license-plate readers threaten much of the privacy we've always enjoyed, on the road and at our destinations of choice, as never before.

These devices garnered a bit of attention last summer, when the ACLU reported on how many states and localities have installed them on patrol cars, bridges, and highway overpasses, where they capture images of every passing vehicle. The intention is often to find stolen cars or to catch drivers evading warrants for their arrest. Yet in most cases, "these systems are configured to store the photograph, the license plate number, and the date, time, and location where all vehicles are seen—not just the data of vehicles that generate hits," the ACLU explained. "All of this information is being placed into databases, and is sometimes pooled into regional sharing systems .... All too frequently, these data are retained permanently and shared widely with few or no restrictions on how they can be used."

The potential for abuse was obvious.

Now the federal government intends to build a national license-plate-reader database. A Department of Homeland Security spokesperson told Ars Technica that Immigration and Customs Enforcement (ICE), "is exploring the ability to obtain access to a National License Plate Recognition database—allowing officers and agents to identify subjects of ongoing criminal investigations."

The Washington Post got an official response too. "It is important to note that this database would be run by a commercial enterprise," ICE said, "and the data would be collected and stored by the commercial enterprise, not the government." Is that supposed to reassure? A private database that's inaccessible to the government would offer some protections. So would a government database that no private entity could exploit. A database of our movements that is privately held and accessible to the government is the worst possible combination.

The logic of license-plate monitoring is similar to that used by NSA officials who insist on collecting data on the phone calls of millions in hopes of catching a few bad guys. If the federal government has its way, the car trips of millions of innocents will be collected and stored in a database. Drive somewhere in 2014, and 10 years from now a bureaucrat could look up where you went on a given Tuesday.

The potential for abuse is obvious. So is the contempt the people behind the policy have for democracy. A proposal to significantly expand surveillance on everyday life ought to have been debated by the public. Instead, it was discovered when the government posted an ad so it could build the national license-plate database. Those behind the effort apparently didn't see a need for public buy-in.