Kaminer, who was on the ACLU board until 2006, criticizes the organization for showing an increasing bias favoring typically liberal causes in choosing the cases it accepts. What I've admired most about the ACLU is its record of commitment to protecting speech which, if it is to mean anything, means protecting unpopular speech. Historically, the politics of those the ACLU represented had not been a noticeable factor in its selection of cases.
There are defenders of the ACLU on the right and the left who understand that it is only unpopular speech that needs protection. Likewise, there are knee-jerk critics of the ACLU on the right and the left who do not understand this simple idea because all of their opinions are automatically processed through the lens of tribal interest and self-interest.
Defending the speech of those opposed to one's own interests is incomprehensible to the self-interested "tribesman." I don't believe this type knows what it means to to take a principled position rather than a narrowly self-interested position because they don't know what principles are. They may know of and even use the word, but it's like one of those empty file folders on your computer. They've got a principles folder, but it's empty because they haven't a clue about what belongs inside that folder.
So, it is disconcerting, indeed, if the ACLU is becoming another organization that places politics above principle. Ed Brayton at Dispatches from the Culture Wars has more of the story and some thoughtful observations here.