The Supreme Court has decided to clear two officers over the 2003 death in Nara, after more than a decade of legal to- and fro-ing, Kyodo and public broadcaster NHK said.
The court's No. 3 Petty Bench has formally rejected an appeal against two lower court rulings clearing Motofumi Hagiwara and Yoshihiro Higashi of killing Sojitsu Ko while he was in the front passenger seat of a moving vehicle.
The ruling is expected to be finalised soon, the reports said.
Nara District Court found in 2012 that Ko died as a result of two shots fired by the police officers to stop the fleeing vehicle.
But it ruled the officers were aiming at the driver's arm and did not intend to kill anyone. Ko, 28, was suspected of theft at the time. The Osaka High Court later upheld the ruling.
Reports from some online media outlets said Ko was an ethnic Korean, although it was not clear if he possessed South Korean citizenship.
In the years following the police killing, prosecutors decided not to build a case, but the district court accepted a request by Ko's relatives to try the officers, with court-appointed lawyers serving as prosecutors.
The facility, while not very common, can be used when public servants have been exempted from indictment, but are suspected of abusing their authority. It is generally conceived of as a way to obviate the often-cosy relationships that can exist between prosecutors and the police.
Ko's relatives also lodged a 100 million yen ($835,000) damages suit over the shooting, but lost it after the top court determined the officers' use of firearms was legal, Kyodo said.
No immediate confirmation of the reports was available from the supreme court.
Although nearly all police in Japan are armed, officers rarely draw their weapons. There are usually only a handful of fatal shootings by law enforcement over the course of a decade.
The police enjoy a large measure of public trust in Japan, despite a growing recognition of the scale of wrongful convictions brought about through forced confessions.