The Massachusetts State Police have been tracking the license plates of every vehicle that enters and leaves Cape Cod every day for the last three years.

That means more than 100 million trips have been recorded and stored in a growing — if opaque — database.

While authorities say they use the technology to find and monitor suspects involved in drug trafficking, kidnapping and other violent crimes, privacy advocates are concerned about how, when and why the information is stored and used.

Are the privacy concerns legitimate or do law enforcement agencies need to be able to track license plates to do their job? Where should the line be between public safety and privacy?

Guests

Wheeler Cowperthwaite, courts reporter at the Cape Cod Times. He tweets @WheelerReporter.

Kade Crockford, director of the Technology for Liberty Program at the Massachusetts ACLU. She tweets @onekade.

Daniel Linskey, former Boston Police Chief. He’s now managing director for Kroll Security Risk Management practice and a fellow at the Duff & Phelps Institute. He tweets @ChiefLinskey.