While troubling limits continue to be placed on our access to the government's information, the same can not be said for government agencies, who are increasingly privy to a startling amount of data on the everyday comings and goings of a law-abiding public.

We've known for some time that it's possible to legally slap a tracking device on a loved (or hated) one's car, with few regulations. (The tracker must hold at least partial ownership over the vehicle.) But who needs a suspicious spouse when drivers are enabling their own tracking through their E-ZPasses?

The NYCLU today submitted a FOIL request to various city and state agencies—including the Department of Transportation and the NYPD—to determine how data obtained through strategically located E-ZPass readers is being used.

“New Yorkers have a right to know if their use of toll-paying technology is secretly being used to track their innocent comings and goings,” said NYCLU Executive Director Donna Lieberman in a statement. “No one should have to trade their privacy to pay a $10 toll.”

The request doesn't bother to ask if the data is being used—we've known that for months, ever since an activist called Puking Monkey (yes) jury-rigged his own E-ZPass to illuminate the face of a toy cow every time it was read. It's not unreasonable to assume that the device would trigger at, you know, toll plazas, but Puking Monkey found that the cow glowed blue all over Manhattan.

The cow might be cute, but what it symbolizes is not: Mariko Hirose, a staff attorney at NYCLU, said how driver's data is used once collected is entirely unknown. "People get [the E-ZPass] to pay tolls and have no idea they're being scanned," she said. "How much it can be used to paint details of our lives about where we've been and where we’re going?"

Another question addressed in the FOIL is whether the data is being combined with other identifying information—and whether it's being shared with law enforcement agencies like the NYPD.

Ostensibly, the readers are collecting information for an initiative called Midtown in Motion, which feeds information from cameras, microwave motion sensors and E-ZPass readers installed at 23 intersections "to measure traffic volumes, congestion and record vehicle travel times in the approximately 110-square block area bound by Second to Sixth Avenues and 42nd to 57th streets." Additionally, a spokesperson for DOT told Forbes in September that readers are also located "on highways across the city, and on streets in Manhattan, Brooklyn and Staten Island, and have been in use for years." (Midtown in Motion launched in 2011.) The agency was cagey about what information was collected from the passes, and how long that information was kept.

In the meantime, drivers who would like to avoid being traced should pop their toll tags in a Faraday Cage when not in use. Want to make your own E-ZPass reader-alert? Puking Monkey generously offers instructions on how to hack your device—just be careful to mind the fine print.