The Supreme Court has ruled that the collection of data through the Global Positioning System in police investigation without a warrant is illegal, and the National Police Agency immediately told police forces nationwide to halt the practice. The top court called for new legislation to cover the use of GPS by the police for investigation purpose, raising doubts about the procedure of issuing warrants for the use of GPS devices in criminal probes under current provisions of the Criminal Procedure Law. The Diet should immediately establish a legal framework to set clear-cut procedures and scope for police collection of GPS data to prevent arbitrary use of the technology by investigators.

The defendant in the case concerning serial theft committed mainly in the Kansai region in 2012-2013 contested the legality of warrantless surveillance through the use of GPS devices. The Osaka District Court ruled in 2015 that the warrantless collection of GPS data in the investigation was illegal and struck the evidence thus collected. Last year, the Osaka High Court determined that the police investigation in this case did not involve serious illegality, without handing down judgment on whether the police needed to obtain a court warrant for collecting the GPS data. The Supreme Court ruled that the warrantless GPS data collection was illegal, although it upheld the 5 1/2 year jail term on the defendant meted out by the lower courts.

During the investigation, the police installed 16 GPS tracking devices on vehicles owned by the defendant and other suspects over several months. Their action followed an internal manual issued by the NPA that allowed warrantless collection of GPS data for the investigation of such crimes as kidnapping, confinement and serial thefts in view of the need for immediate action and the difficulty of tracking suspects by other means.

Court rulings on other cases resulted in mixed judgments on warrantless investigations relying on GPS devices. The March 15 ruling by the Supreme Court represented the unified position of the judiciary over the issue. It was a unanimous decision by all 15 justices on the Grand Bench.

In the trial, the prosecution argued that GPS data collection falls under the same category of investigation as police staking out or trailing suspects — acts that don’t require a court warrant — and is outside the sphere of coercive investigation, which requires a warrant.

Referring to Article 35 of the Constitution, which says that “the right of all persons to be secure in their homes, papers and effects against entries, searches and seizures shall not be impaired” except upon duly issued warrant, the Supreme Court said such right includes the right not to be intruded on in one’s private sphere. Noting that investigation using GPS devices “suppresses” individuals’ will and violates their important legal rights as guaranteed by the Constitution, the top court determined that such a probe constitutes coercive investigation and will therefore requires a warrant. It specifically said that since GDP data collection enables the police to continuously and comprehensively grasp the position and movement of the target of investigation, it inevitably leads to intrusion into the private sphere by government authority.

A key feature of such an investigation is that the police can obtain various types of personal information — such as the targeted person’s relationships with other people and his or her thoughts and beliefs — by accumulating and analyzing the targeted person’s position and movement, including in spaces where privacy must be protected. Even a court warrant for such an investigation cannot prevent investigators from grasping information about the target unrelated to the offense being probed, the top court pointed out. Given the principle that a warrant needs to be presented to the suspect in advance — and that GPS data collection on the target will need to be carried out in stealth — the court called for new legislation that covers the use of GPS devices in criminal investigation.

The serial theft case handled by the Supreme Court highlighted problems in the NPA manual on investigation using GPS devices. While the defendant was arrested in December 2013, it was only in the spring of the following year that the prosecution let his defense know about the police collection of GPS data in his case. Until then, the police hid their GPS-based probe even from public prosecutors. The manual tells investigators not to inform the suspects of their use of the GPS devices during their questioning and not to record the fact on investigation documents.

The new legislation needs to take into account the rights of targeted people while allowing the use of devices that can track and grasp their actions continuously and comprehensively for investigative purposes — which may include not just GPS devices but bugging equipment to eavesdrop on conversations involving the targets or the use of face authentication systems in criminal investigation. An important point should be to ensure transparency in the procedure for investigations that rely on these devices.

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