Security

US Court: Police Must Obtain Warrant To Track Mobile Phones

Matt Broersma is a long standing tech freelance, who has worked for Ziff-Davis, ZDnet and other leading publications

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A felony conviction in Washington DC has been thrown out over police’s use of a mobile phone tracking device without court approval

A Washington DC appeals court has ruled law enforcement officials must obtain a search warrant before using a device that pinpoints a mobile device’s location, concluding that the device’s use otherwise would violate the US Constitution.

The Washington DC Court of Appeals said on Thursday that the use of devices such as the StingRay II, made by Harris Corp., violates the Constitution’s Fourth Amendment, which prohibits unreasonable search and seizure, unless a warrant is obtained first.

Landmark case

The devices have been used by US police and federal agents for years, but civil liberties advocates have argued restrictions should be placed upon how they’re deployed.

The ruling, which is the fourth such by a state appeals court or federal district court, agreed with that position and is likely to decide the issue unless the government appeals.

harris-stingray-ii
Harris Corp.’s StingRay II

The government could ask for a rehearing by the three-judge panel or the entire appeals court, and if the request is denied could take the case to the US’ Supreme Court. But the Supreme Court might decline to hear a case upon which all lower court rulings have been in agreement.

The Maryland Court of Special Appeals and federal district courts in New York City and San Francisco previously reached similar rulings on the use of cell-site simulators.

The appeals court’s ruling threw out the 2013 conviction of Prince Jones, in the investigation of whom Washington DC police used a StingRay to locate Jones’ location without first seeking court approval.

Jones had been convicted on nine felony counts of sexual abuse, kidnapping, armed robbery and threats, but the evidence against him was thrown out because it had all been obtained due to the use of the StingRay to locate him.

Jones had allegedly arranged to meet with two women who he then assaulted and robbed, in both cases taking the victims’ mobile phones.

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‘Invasion of privacy’

Police found that the same mobile number was used to arrange the meetings through a website called Backpage.com, and obtained identification numbers for the device and the two stolen phones, according to court records.

They then worked with the mobile phone companies linked to the three phones to determine the general location, where they all appeared to be found in the same place. After travelling to the area they switched on the StingRay and tracked the assailant’s phone to a parked car in northeast Washington D.C., where Jones was sitting.

The identification of Jones later led to the discovery of the knife apparently used in the robberies, the discovery of the victims’ phones and incriminating statements made by Jones and his girlfriend, but all this evidence was thrown out due to having been obtained through unauthorised use of the StingRay.

The court and the defence agreed that if police had used the StingRay to locate the victims’ phones, instead of that of Jones, the search would have been legal, since the victims consented to the search.

“The use of a cell-site simulator to locate Mr. Jones’s phone invaded a reasonable expectation of privacy and was thus a search,” wrote associate judge Corinne A. Beckwith in the appeals court’s ruling.

Civil liberties issue

Cell-site simulators, which cost around $500,000 (£370,000) trick devices into connecting to them instead of a mobile company’s phone masts and are capable of locating the devices more precisely than a phone company can.

NetworksThe American Civil Liberties Union (ACLU) said it knows of 72 cell-site simulators in use in 24 states and D.C., but estimates many more have quietly been deployed.

“We applaud today’s opinion for erecting sensible and strong protections against the government violating people’s privacy in the digital age,” said the ACLU’s Nathan F. Wessler, who helped the DC Public Defender Service argue the case.

The Washington DC US attorney’s office declined to comment.

In 2015 the US Justice Department tightened its rules on the use of the StingRay, advising its agencies to obtain a search warrant, and the DC Metropolitan Police Department has said it would follow the policy. The appeals court ruling, however, is a step toward cementing the rule into law.

A 2015 investigation found police and other security forces were using StingRay devices to routinely track the movements of British mobile users.

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