The move, announced in a news release Friday, is at odds with Mitchell's past public support of Disney governance rules requiring directors to retire when they reach 72, his current age.
When Roy E. Disney quit as a director in 2003 after learning that he would not be nominated for another term, it was Mitchell who publicly defended the board's move as simply enforcing Disney's rules.
Disney spokesman David Caouette said the board had the flexibility to waive the policy requiring mandatory retirement at age 72 and chose to do that in Mitchell's case. Mitchell turns 73 in August.
But Gregory P. Taxin, chief executive of the proxy firm Glass Lewis, said Mitchell should step down as planned.
"We don't believe he has been effective, we don't think he is independent, and we think he should go," Taxin said
Taxin, however, noted that Pepper was on the Xerox Corp. board of directors when the company improperly recorded $6.4 billion of revenue.
The restated financials reduced Xerox's revenue by $1.9 billion from 1997 to 2001 and led to a $10-million fine to settle Securities and Exchange Commission fraud charges. Pepper was on the audit committee that failed to catch the costly accounting problems, Taxin said.