The case of Yount v. City of Sacramento arose out of an incident in which a police officer, who was attempting to subdue an intoxicated suspect resisting arrest, attempted to shoot the suspect with a Taser -- but accidently drew the officer's service pistol and shot the suspect in the buttock. The suspect pled no contest to obstruction of an officer's performance of duties (California Penal Code section 148.) He then sued the officers under 42 USC section 1983 for violation of his fourth amendment right to be free from excessive force; and under state law for battery.
The California Supreme Court addressed whether Heck v. Humphrey (1994) 512 U.S. 477 barred the plaintiff's section 1983 claim; and whether analogous state law barred his battery claim. Heck holds that a party cannot collaterally attack a criminal conviction by a civil lawsuit. Therefore, a section 1983 suit against police by a plaintiff who has been convicted of a crime is barred if a judgment in the plaintiff's favor would require negating a basis for the conviction.
The court concluded that plaintiff's plea of no contest to the obstruction charge -- combined with eyewitness testimony concerning the events leading up to the arrest -- triggered Heck, barring him from arguing in the civil suit that the police violated his fourth amendment rights just by using force against him. That was because the crime of obstructing an officer justifies a reasonable use of force by the officer. But to the extent the plaintiff sued the officers for using excessive force -- specifically, unwarranted lethal force -- the suit survived Heck. The same principles applied to the state law battery claim.
The court declined to decide whether an officer's accidental use of lethal force -- as is alleged here -- would suffice to support a section 1983 or battery claim, both of which require intentional misconduct (or at least reckless disregard for another's rights).