Records of every trip a motorist takes on an electronic toll road over a five-year period is fair game for divorce attorneys and others given access to California's FasTrak system. The device records the location, date and time that a vehicle equipped with a transponder passes a tolling checkpoint. The data is held indefinitely.

A Contra Costa Times investigation earlier this month found about twenty subpoenas used in the past two years to gain information about a handful of the 620,000 FasTrak users in the San Francisco Bay area who crossed one of eight toll bridges. Divorce lawyer Alexandra Mussallem uses FasTrak to build a case.

"We often have arguments about whether or not one spouse works to his or her maximum earning capacity," Mussallem told the Times. "If someone hits the Bay Bridge toll plaza at noon on a day he said he was working, you know he's not working. He might be with his girlfriend in Contra Costa County."

FasTrak has an unadvertised anonymous account option for motorists who do not wish to be tracked. A FasTrak device -- which still has a serial number and is tracked -- is linked to an account with no personal details. The motorist may go to a service center in person to update the account with cash.