A recent investigation by USA Today showed that police in Baltimore have been tracking cellphones during investigations but have failed to disclose the tracking to defendants and their attorneys. As a result, public defenders in Baltimore are expected to request that "a large number" of criminal convictions be thrown out. Baltimore police have used cellphone trackers, commonly known as stingrays, to investigate crimes as minor as harassing phone calls, then concealed the surveillance from suspects and their lawyers. Maryland law generally requires that electronic surveillance be disclosed in court. […] Stingrays are suitcase-sized devices that allow the police to pinpoint a cellphone’s location to within a few yards by posing as a cell tower. In the process, they also can intercept information from the phones of nearly everyone else who happens to be nearby.