Roman Polanski will attempt to appeal the Academy of Motion Picture Arts and Sciences’ decision to expel him, Polanski’s attorney, Harland Braun, has told Vanity Fair.

“We want due process,” Braun said. “That’s not asking too much of the Academy, is it?”

The Academy’s Board of Governors met on Tuesday night and voted to expel Polanski and Bill Cosby from its membership, in accordance with the organization’s new standards of conduct.

Polanski pleaded guilty to unlawful sexual intercourse with a minor in 1977 and fled the country after serving 42 days, when it seemed he might be sent back to prison. Polanski’s legal history did not seem to trouble many Academy members in 2003, when he won an Oscar for directing The Pianist and received a standing ovation at the Academy Awards ceremony; presenter Harrison Ford accepted the trophy on his behalf.

But times have clearly changed, particularly since the Academy expelled Harvey Weinstein in October, and instituted new rules for reporting member misconduct in January. When she announced those new rules, Academy C.E.O. Dawn Hudson told Oscar voters in an e-mail, “The Academy’s goal is not to be an investigative body, but rather ensure that when a grievance is made, it will go through a fair and methodical process.”

Braun believes the Academy failed to follow a fair process in this case.

“Mr. Polanski was supposed to be given notice, and have 10 days to present his side,” Braun said. “It was a complete debacle in the sense that they didn’t follow their own rules.”

Braun said he had heard the Academy was planning to take up the issue of Polanski’s membership, and he was prepared to make a presentation to the board, which would include statements from the victim in his 1977 case, Samantha Geimer. Reached separately on Thursday, Geimer, too, objected to the Academy’s decision, calling it “ugly and cruel” and “just P.R.”

“They short-circuited it all,” Braun said. “It’s shocking that they’re so unfair. We’re going to try to sit down with the Academy and say, ‘Hey, look, guys, follow the rules.’”

The Academy’s bylaws include a line that gives its board the authority to expel a member as long as two-thirds of Academy governors approve. The board retains that authority under the new rules passed in January.

A spokeswoman for the Academy declined to comment on whether the board would hear an appeal from Polanski.