A US Appellate Court has ruled that police must obtain a warrant before collecting cellphone location data, finding that acquiring records of what cell towers a phone connected to and when it was connected to them constitutes a Fourth Amendment search. In its reasoning, the court notes that while the Fourth Amendment has traditionally been applied to property rights, its gradually expanded to protect much more, including communications. In the 20th century, a second view gradually developed, the court writes, that is, that the Fourth Amendment guarantee protects the privacy rights of the people without respect to whether the alleged search constituted a trespass against property rights. In particular, the court cites a Supreme Court ruling that found that tracking a person using a GPS unit installed in their car requires a warrant.