From an editorial in the Asahi Shimbun:
The Osaka District Court decided in favor of the police in a privacy case that raised questions about whether they have the authority without a warrant to secretly attach global positioning system (GPS) devices to the cars of suspected criminals to track their movements.
In the Jan. 27 decision, the court said that police did not violate the law when they used GPS devices to monitor vehicles during a theft investigation. It said there was “no serious illegality” in the way the police acted.
But secret use of GPS tracking devices in criminal investigations could be seen as a violation of basic privacy rights guaranteed by the Constitution and should not be allowed without serious debate on its implications and other issues.
Read more on The Asahi Shimbun.