A lawyer for Brock Turner, whose six-month jail sentence for sexually assaulting an unconscious woman prompted outrage in 2016 and beyond, argued this week that the former Stanford swimmer shouldn’t have been convicted of intending to commit rape because he merely sought “outercourse.”

The lawyer, Eric Multhaup, made that argument before a three-judge panel of California’s Sixth District Court of Appeal in San Jose on Tuesday. Mr. Turner is appealing his conviction on charges of sexual assault of an unconscious person, sexual assault of an intoxicated person and sexual assault with intent to commit rape.

The 22-year-old victim was attacked after a fraternity party in January 2015. Two witnesses said they found Mr. Turner, then 20, thrusting on top of her unconscious body by a dumpster near the fraternity house, her dress pulled above her waist. He told the police that he removed her underwear and penetrated her with his fingers, but never took his own pants off.

During Tuesday’s court appearance and in a brief filed in May, Mr. Multhaup argued that the “outercourse” — defined as sexual activity other than vaginal sex — was all Mr. Turner sought.