The BART Police Department stripped its officers of Tasers on Thursday, days after a sergeant fired the electric darts of his stun gun at a 13-year-old boy fleeing from police in Richmond on his bicycle, sources told The Chronicle.

BART officials, who said officers would be retrained to use the devices, attributed the decision to the Richmond incident as well as a recent federal court ruling that narrowed the circumstances under which police can use Tasers.

The officials said they could not comment on the Richmond case, citing privacy laws that apply to internal investigations. Interim Police Chief Dash Butler said only that the incident accelerated plans that were already in progress to retrain officers and update policies on the proper use of Tasers, which BART police began using in December 2008.

Sources familiar with the matter, however, told The Chronicle that a veteran sergeant in a moving patrol car fired his Taser several days ago at the 13-year-old boy, who was fleeing from an altercation at BART's Richmond Station on a bicycle.

The darts missed the boy, said the sources, who spoke on condition of anonymity. They said the sergeant, who has taught defensive tactics at BART, remained at work but had been removed from street duty.

Butler said the suspension of the Taser program would allow the department to do training that integrates rulings by the Ninth U.S. Circuit Court of Appeals that have already prompted changes at agencies around the Bay Area.

The most pivotal ruling came in December, when the court said a man could sue a Coronado (San Diego County) police officer who had stunned him with a Taser to gain compliance after pulling him over for failing to wear a seat belt. The man was "yelling gibberish and hitting his thighs," the court said, but did not pose an immediate threat to the officer.

"We were planning on doing this a few weeks down the road," Butler said of pulling Tasers off the streets, "and (the Richmond incident) accelerated it."

New rules

Butler said BART's Taser policy has always barred officers from using the devices to stop fleeing suspects, and will continue to do so. He said the new policy forbids using a Taser on a minor "unless there's some exigent circumstances."

"Let's say," he said, "you had a 17-year-old who was 6-foot-4 and 200 pounds and was pounding on an officer and the officer couldn't escape. The officer could use a Taser."

Butler said BART's new policy will also forbid officers from pulling and firing Tasers with their strong hand - their gun hand. When officers resume carrying Tasers, he said, right-handed officers will have to keep the devices on their left hip and deploy them with their left hand.

"The real common sense of it," Butler said, "is you don't want to put that device anywhere near the handgun. Potentially, you could have confusion. We don't want that possibility. Just put them on the weak side."

Tasers in Grant case

BART's Taser program has been under scrutiny since a former officer, Johannes Mehserle, shot and killed unarmed train rider Oscar Grant on Jan. 1, 2009, at the Fruitvale Station in Oakland.

Attorneys for Mehserle, who faces a murder trial this summer, say he meant to stun Grant with a Taser and accidentally fired his service pistol.

The Chronicle reported earlier this year that Mehserle had borrowed a Taser and a special holster for the device from a colleague a few hours before the shooting. At the time, in a cost-saving move, BART forced officers to share both Tasers and holsters.

Mehserle, though, did not adjust his colleague's holster, a task that would have demanded up to 15 minutes of work with an Allen wrench and a Phillips-head screwdriver. Instead, Mehserle wore the holster in a way that required him to draw the Taser with his right hand - his gun hand.

But there are indications Mehserle was accustomed to a left-handed draw for a Taser. A source familiar with his training said that's the way he preferred to wear it.

John Burris, an attorney representing Grant's family, said Thursday that if an officer fired at a fleeing teenager on a bike, "that's outrageous. I can't imagine there's a justification for that use of force. You create undue danger that the person may fall off the bicycle, and either hit someone else or be killed."

Burris called the temporary suspension of the Taser program "a very positive step" for BART.

Burris said, "It's important that this retraining take place before someone else is seriously injured or killed."