In the Washington Post this weekend, Tom Jackman wrote about a legal threat to the use of cell phone records to provide evidence to a person’s location.
Cell phone records are often used in court to testify to a defendant— or others— being in the vicinity of a crime.
The location information is determined based on an analysis of the cell phone towers a phone “pings” off of. Generally, a person’s phone, if proved to be with them, can provide evidence of where a person is (but not their exact location).
Cellphone records are often used as evidence, relied upon to trace which cell tower was used to make or receive a call and then determine a caller’s whereabouts. But experts say that using a single tower to precisely locate where someone was at the time of a crime has severe limitations. And while defense lawyers are gradually recognizing the problems with such evidence, the FBI continues to rely heavily on the data in its investigations. The agency wants to expand its full-time team of 32 agents dedicated to the analysis of cell-site data, and it has trained more than 5,000 state and local police investigators in the basic methodology.
The conflict between the growing awareness of cell records’ limitations and the FBI’s desire to expand their use is increasingly forcing the nation’s judges to parse the technical evidence and determine if it’s being used fairly. In recent federal cases in Portland, Ore., and Chicago, judges have ruled that the analysis of cellphone records was not scientifically valid or reliable in locating people, in part because investigators have overstated its accuracy. In the hundreds of trials where judges have allowed the evidence, some defense lawyers have persuaded juries to acquit defendants of kidnapping and murder.
Read the full story here.