SAN JOSE -- Amid a raging public debate in 2011 over San Jose police tactics and use of force, an Air Force veteran was thrown to the ground and zapped twice with a stun gun after mouthing off to cops during a traffic stop. Later this week, a judge will decide whether to hold police liable for their behavior in a case that is awakening memories of a difficult era the department hoped it had left behind.

The case stems from a downtown traffic stop in early 2011, just a few days after newly appointed police Chief Chris Moore vowed to rebuild community trust after a series of incidents spawned criticism that the department used excessive force against Latinos, Asians and blacks. Reports in this newspaper found the department had a history of disproportionately arresting Latinos for minor conduct that would warrant a mere citation elsewhere. And a cellphone video appeared to show officers beating and using a stun gun on a passive and unarmed Asian college exchange student in his apartment as he groped for his eyeglasses.

The current trial stems from a lawsuit filed by Air Force veteran Michael Fujikawa. The only passenger in his brother's older black BMW, he claims he was thrown to the ground during a 1:45 a.m. downtown traffic stop, zapped at least twice with a stun gun and jailed for five days on inflated charges as payback for initially refusing to put his hands on the dashboard and mouthing off to Officer Steven Payne Jr.

Eleven months later, just before Fujikawa was to stand trial on battery and resisting arrest charges, prosecutors dropped the case. Fujikawa then sued San Jose, Payne and two other officers, Brian Jeffrey and Daniel Pfiefer, seeking unspecified damages for false arrest, excessive force and violating his free speech rights.

"He was treating us as if we were America's most wanted," Fujikawa testified last week.

The officers have denied violating Fujikawa's civil rights, saying they feared for their safety and handled the incident at the intersection of Fourth and San Fernando streets by the book.

It will be up to Santa Clara County Superior Court Judge Beth McGowen to decide whether the city is liable and must pay general and punitive damages. Both sides agreed not to summon a jury for the trial.

Normally, police have the upper hand in such credibility contests. But Payne's explanation of what triggered the confrontation -- that Fujikawa never complied with his order to put his hands on the dash -- is potentially undermined by a discrepancy between his police report and the department's own GPS records about his location, among other things. Another officer testified that when he arrived about a minute after Payne arrived, Fujikawa's hands were on the dash.

And Payne was the officer seen in the controversial 2009 video shocking an unarmed San Jose State student with his Taser, although then-District Attorney Dolores Carr declined to charge him and other officers in that incident. In addition, in a 10-week span in 2008, he used force in four separate incidents as he took people into custody for resisting arrest, an investigation by this newspaper revealed.

Although Payne did not lay a hand on Fujikawa in this case, Fujikawa's lawyer Michael J. Reiser alleges he overreacted when Fujikawa said "F--- you" and improperly instructed the other officers to take him into custody, which they did using what the lawyer claims was excessive force. Fujikawa testified that he immediately apologized for the insult.

But Payne testified he was not enraged by Fujikawa's insult, telling the judge, "People say that to me all the time, and worse." The officer said he was just concerned that Fujikawa had been making "furtive" movements, was screaming and refused to obey. State law requires all passengers as well as the driver to comply during a traffic stop.

Payne claims in his police report that he followed Fujikawa's brother David's car along First, Santa Clara and Market streets, and for four blocks on San Fernando Street. He noted that the driver was traveling at unsafe speeds, changed lanes four times within one block without using his blinker and followed another vehicle too closely. In court, Payne also testified the occupants of the car yelled at passers-by in an intersection and were playing music extremely loudly.

However, the routes described by the driver and Fujikawa don't match that account. And GPS records kept by the department show Payne was blocks away for a portion of the time and therefore could not have seen all that he described.

Payne blamed the tracking system.

"It's off a lot," he said. "Every officer sees it. It's common knowledge around the department."

But a police official who oversees the system testified she has no evidence that the system wasn't working that night. And an expert hired by the plaintiff testified that the 12-satellite receiver unit system police use offers the most accuracy available, which is plus or minus about 16 yards, roughly the length of three mid-size sedans, even when the signal has to bounce off tall buildings.

But the system indicated Payne's car was almost 337 yards away from the location he put in his report -- 20 times farther away than the worst-case error.

Contact Tracey Kaplan at 408-278-3482. Follow her at Twitter.com/tkaplanreport.