Another American Civil Liberties Union board member who clashed with leaders of the group has been voted off the organization’s national board.

An attorney and veteran civil rights activist, John Brittain, was the only person among 12 at-large candidates to fail to get enough votes to win election or re-election, according to a tabulation done last week.

“I’m free at last, at least from the ACLU,” Mr. Brittain quipped in an interview from Washington, where he serves as chief counsel to the Lawyers’ Committee for Civil Rights Under Law.

Mr. Brittain, who has served more than five years on the ACLU board in two stints, said he believes his ouster was tied to a recent controversy over a proposal some viewed as an attempt to prevent board members from publicly airing disagreements with the organization.

“I feel I was probably purged,” Mr. Brittain said.

In June, after protests from members and donors, the board effectively tabled the proposal on the “rights and responsibilities”of board members, though the measure was not formally voted down. A few weeks later, the ACLU issued an unusual public statement in which the head of the committee that drafted the report said the most contentious language would not be resubmitted.

Mr. Brittain said some board members strongly objected to his decision to tell others on the board that an attorney from the office of the New York attorney general, Eliot Spitzer, had called to raise concerns that the proposal might interfere with board members’ duties to report misconduct. The matter was discussed by the board’s executive committee, on which Mr. Brittain sat, but the committee voted over his objection not to disclose the call immediately to the larger board.

The disclosure led to a New YorkTimes article about the call from Mr. Spitzer’s office, though Mr. Brittain insists he disclosed the call only to other board members, which is not prohibited by ACLU rules. “Despite the fact that there was no rule or policy, I was vehemently and angrily and hostilely criticized by some,” Mr. Brittain said. “It rubbed a lot of people the wrong way.… I didn’t have to subject myself to that kind of animosity to serve on a nonprofit board.”

Board members said Mr. Brittain may have also ruffled feathers by writing to the ACLU president, Nadine Strossen, to object to the procedure by which the proposals on board responsibilities were repudiated publicly without action by the board or its executive committee.

Last year, the ACLU voted a vocal dissident, Michael Meyers, off its board. Another critic of the organization’s leadership, Wendy Kaminer, left in June after choosing not to run for re-election. However, the departure of Mr. Brittain is notable because he was rarely quoted in the press and generally confined his critiques to board meetings and online discussions among board members.

“Is the bar becoming so low that you can’t even look askance?” one current ACLU board member, who asked not to be named, said.

Asked if Mr. Brittain’s decision to tell board colleagues about the call from Mr. Spitzer’s office played a role in his defeat, a board member from Los Angeles, Alan Toy, said: “I think any board member’s actions are noticed by the other board members and the electorate at large. You represent a large group of people, and people notice things and they vote accordingly.”

Asked if there was an organized effort to oust Mr. Brittain, Mr. Toy said, “There’s always a certain amount of politicking.”

Mr. Brittain and his supporters conceded that one factor in his defeat may have been his failure to campaign actively, though some insiders said it was still extremely unusual for an incumbent board member to be defeated.

Ms. Strossen did not respond directly to an interview request, but a spokeswoman for the ACLU, Emily Whitfield, defended the group’s electoral process.

“The national board election is a result of representative democracy. We believe in it, we practice it, and it works,” Ms. Whitfield said. She added that ACLU staff members are barred from involvement in the election.

Ms. Kaminer said the ouster of Mr. Brittain undercut claims that she and Mr. Meyers were driven out because they were overly confrontational and rude. “You’d be hard pressed to find a more gentlemanly, decent guy than John Brittain. If he dissented, he did it most civilly,” she said.

Mr. Meyers, who is friendly with Mr. Brittain, called his defeat “scandalous and indecent.” He also noted Mr. Brittain’s role as one of the earliest African-American activists in the group. “When the ACLU was lily white and people thought no black civil libertarian would support the right of the KKK to exist and to march, and the right of the Nazis to march in Skokie, John Brittain was across-the-board a civil libertarian. He’s come up in the ACLU,” Mr. Meyers said.

Ms. Whitfield said minority representation on the board and staff is strong and growing, but Mr. Meyers said the numbers were achieved by electing a relatively small number of people who met multiple diversity goals.