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In a 5-4 vote, the United States Supreme Court ruled on Friday that police must first obtain a search warrant before examining location data — cell tower records that can show a person’s movement for long periods of time — stored on a subject’s mobile phone.

The decision is considered to be a major victory for individual privacy rights.

“The four dissenting justices, however, warned that the court’s ruling could tie the hands of police,” according to the Los Angeles Times .

Chief Justice John G. Roberts Jr. noted that people today “compulsively carry cellphones with them all the time. A cellphone faithfully follows its owner beyond public thoroughfares and into private residences, doctor’s offices, political headquarters, and other potentially revealing locales. Accordingly, when the government tracks the location of a cellphone it achieves near perfect surveillance, as if it had attached an ankle monitor to the phone’s user.”

Roberts wrote, “Whoever the suspect turns out to be, he has effectively been tailed every moment of every day for five years. If the government were allowed to freely obtain that data without getting a warrant, “only the few without cellphones could escape this tireless and absolute surveillance.”

The decision on looking at location data aligns with recent Supreme Court rulings on mobile phones. In 2014, the high court ruled that police must generally get a warrant to search the cellphones of people they arrest.