Oh fucking hell.
Pretty much everyone that I've told that I work for the ACLU has said something positive, but qualified. Like "Oh they're a cool organization, but I don't support everything they do". Or "They've made some bad decisions", or whatever.
But actually, everyone that I know and talk to, you are wrong. Yes, the ACLU defended neo-Nazis right to march down the street in predominantly Jewish town. Yes, they defended NAMBLA (the most tragically funny organization ever), and they defended those disgusting Theocrats from Westboro Baptist Church.
But really, if you don't let the Nazi's march, or you don't let the Westboro idiots yell at soliders and queers, then it just makes the problem worse. The idiotic movements are exposed as what they are by being out the open. If something is prohibited, it just makes it all that more appealing to those that are predisposed toward these ridiculous movements, and it makes violence more likely. Provocation is what these types of groups specialize in, and letting them march out in the open while you drink a cup of tea and act all gay or Jewish or whatever is probably best way to fuck with them (this is why I advocated a big gay dance party counter-protest to the Westboro people when they came to town instead of an indignant, angry counter-protest). Furthermore, I'm willing to bet that the neo-Nazis and the Westboro people have done more to hurt their cause with any publicity they got because the public's reactions are pretty universally disgust.
Anyway, I digress. The point is, I honestly can't think of a court case that the ACLU has been wrong on. They literally persuaded John Scopes to testify on behalf of evolution at the famous trial. They supported school desegregation, Roe v. Wade, and gay rights time after time.
Like Glenn Greenwald says, the ACLU has been the first and most prominent opponent of all the tough guys that have wanted to establish a police state since September 11. For example of the tough guys who love to start wars that they don't fight in, you can always check the Weekly Standard.
Here's Glenn's response to that article.