The use of GPS technology by police has been a controversial issue in the US recently. In November, the US Court of Appeals for the District of Columbia Circuit [official website] declined to rehear en banc [JURIST report] a bid by the US Department of Justice to overturn a decision that prevents the government from using GPS technology to track suspects without a warrant. However, courts have struggled with how to apply Fourth Amendment protections to modern technology. In September, a three-judge panel for the US Court of Appeals for the Third Circuit [official website] ruled [opinion, PDF] that at times the government might need a warrant to obtain cell phone data [JURIST report] to track a person's location. In June, the US Supreme Court unanimously held [opinion, PDF] that, even if there is a reasonable expectation of privacy in work-issued electronic devices, that an employer's search of private text messages does not violate [JURIST report] the Fourth Amendment so long as the search is not excessive and is pursuant to a legitimate work-related purpose.