The American Civil Liberties Union of Massachusetts is launching an online toolkit this week to help criminal defence lawyers determine whether police secretly used surveillance technology to build cases against their clients. Described as the first resource of its kind, it provides ready-made legal motions that, if approved by a judge, compel prosecutors to disclose the use of tools such as facial recognition, licence plate readers, gunshot detection systems and phone-tracking devices. The initiative aims to close a long-standing gap between when police adopt new surveillance tools and when courts eventually rule on their legality, a delay campaigners say is worsened because defendants cannot challenge technology they were never told about.

The toolkit, restricted to verified defence attorneys via a password-protected library, also includes motions demanding that surveillance data be preserved before automatic deletion. It draws on a 1963 legal principle requiring prosecutors to share all evidence that could aid a defendant. The ACLU cites past cases of concealment, including Baltimore police using "stingray" phone trackers more than 4,300 times between 2007 and 2015 under FBI secrecy agreements instructing prosecutors to drop cases rather than reveal the devices, and a Georgia man wrongly identified by facial recognition and jailed for nearly a week after a warrant falsely credited "a credible source" instead of the software used.