A traffic stop and police search that uncovered homemade explosives in a suspected Japanese terrorist's car were conducted legally and the bombs may be used as evidence at trial, a federal judge ruled Friday.

Lawyers for the suspect, Yu Kikumura, had argued that the State Police trooper stopped their client at a New Jersey Turnpike rest area without any cause, found the bombs in the trunk in an illegal search and then lied in his reports and at a pretrial hearing.Trooper Robert Cieplensky testified that the three bombs, manufactured from fire extinguisher canisters, were on the floor in the back seat of Kikumura's car. He said they were visible from outside when he approached after stopping Kikumura for careless driving, giving him probable cause to arrest Kikumura and search the rest of the car.

U.S. District Judge Alfred Lechner said in a 41-page opinion that he found Cieplensky's version of the April traffic stop believable.

"From the viewpoint of detection avoidance, it does appear unwise to transport explosives exposed in the interior of one's car," the judge wrote. "Yet it is often as a result of such lapses of common sense that crimes are detected."

Kikumura, 36, is scheduled to go on trial Nov. 14 on charges of possession of explosives and use of a fraudulent visa. He faces up to a century in prison if he is convicted on all counts.