SAN FRANCISCO (KQED and AP) — A federal appeals court says Oscar's Grant father can proceed with a civil rights lawsuit against Johannes Mehserle, the BART officer who shot and killed his son on a train platform.

The 9th U.S. Circuit Court of Appeals' unanimous decision on Tuesday affirmed a lower court's ruling. It rejected Mehserle's bid for immunity by claiming that he was acting in his official capacity when he fatally shot Grant in the back as the 22-year-old lay facedown on a BART platform early New Year's Day 2009.
Grant and his friends were being detained after becoming involved in a fracas on the train. The incident was captured on video by several bystanders. Mehserle claimed that he mistakenly shot Grant when he thought he was using his Taser. He served 11 months in prison after being convicted of involuntary manslaughter.
The appeals court ruled today that it's up to a jury to determine whether Mehserle was justified in shooting Grant. It also rejected Mehserle's argument that Grant and his father lacked a sufficiently strong relationship to support the father's claim of deprivation of a familial relationship. Grant's father is currently serving a prison sentence for murder.
Oscar Grant's friends who were also involved in the encounter, recently depicted in the film "Fruitvale Station," also brought suit against Mehserle, as well as against BART officers Anthony Pirone and Marysol Domenici. The court today held that Mehserle and Pirone were not entitled to immunity from the friends' claims of improper arrest. The denial of Domenici's immunity by a lower court was vacated and remanded back.