As rapidly evolving technological advances allow people to be tracked by global positioning devices found in most new cellphones, Congress and courthouses nationwide are trying to balance privacy rights with the law enforcement’s need to locate criminals.

U.S. District Judge Susan K. Gauvey in Maryland recently refused to issue a warrant sought by federal authorities to find a suspect through his cellphone’s GPS data, saying the government was trying to use technology in a new way – “not to collect evidence of a crime, but solely to locate a charged defendant.”

The American Civil Liberties Union questions how the GPS data is being used by police. The group said this month that police in Michigan sought information for every mobile phone near a planned labor protest, and that Sprint, in just over a year, received 8 million requests from police for global positioning data...