Professor Reynolds approvingly quotes Professor Volokh (I've linked to Glenn's site, because blogspot permalinks seem to be fubar lately):

By the way, note also that the Washington Post article mentioned below mentioned the "gun lobby." I wonder: Would they have called NARAL and other groups on NARAL's side of the issue the "abortion lobby"? Would they have called the Reporters' Committee for Freedom of the Press the "press lobby"? Would they have called the NAACP the "black lobby"?

I somehow doubt it.

Me, too. As another example, I've commented in the past on the tendency of defenders of the War On (Some) Drugs to use an ad hominem attack, accusing (with no basis) proponents of more rational drug policies of being drug users, or drug user wannabes. As I've said in the past, it's just as odious a tactic as accusing someone opposed to racial quotas of being a racist, as though it's not possible for someone to take a stance on principle.

As Eugene points out, the media is quite selective in their labeling. If it's a liberal/left cause, the group is an "X Rights group," but if it's perceived to be a "right-wing" cause, then the group is labeled an "X group" (no rights need be mentioned).

So, is, for example, the Drug Policy Alliance (formerly the Drug Policy Foundation) a civil rights group (defending the right of people to consume whatever vegetation they desire, and to not have their property invaded or appropriated without a trial), or a "drug use advocacy group"? They believe the former, but the drug warriors attack them as the latter.