The national ACLU has put together an extremely helpful chart outlining which states have proposed or enacted legislation requiring law enforcement to obtain warrants to track our physical locations, in real-time or historically. According to the ACLU’s count, 18 states require cops to get a warrant to conduct location tracking; of those, six require a warrant for both real-time and historical cell phone location surveillance.

In some states there are no statutes regulating police cell phone location spying, but courts have ruled to provide some protections. In Massachusetts, for example, the state’s highest court ruled in Augustine (an ACLU case) that law enforcement must obtain a probable cause warrant to demand two weeks of historical cell site location information from a phone company. That important ruling provides some protections, but we need the state legislature to pass the Electronic Privacy Act to fill in the gaps. The legislation would require police to get warrants to track us in real-time, or obtain even one piece of historical location data from our cell phone companies.

Take action now to urge your state legislators to support this basic privacy reform.

See the ACLU’s chart to find out the status of cell phone tracking law in your state. Keep in mind that these laws only govern state and local police, not federal agencies or even local police who have been deputized as federal agent to work on drug or terror task forces. Some federal appeals courts have ruled on the issue, but in most places nationwide there is no law restricting federal agents’ power to track our locations without warrants. Ultimately, we need congress or the Supreme Court to establish clear federal law requiring law enforcement at every level to obtain a warrant before tracking our phones. The bipartisan GPS Act would do just that.