The American Conservative Union (ACU) is an American political organization advocating conservative
policies, and is the oldest such conservative lobbying organization in the country. The ACU is well-known for its
annual ranking of politicians according to how they vote on key issues, providing a numerical indicator of how much the
lawmakers agree with conservative ideals.
As the ACU puts it, "The [Congressional] votes selected [to determine the ACU's rankings] are chosen to create a clear
ideological distinction among those casting them." A Member of Congress's overall score is divided by his or her
number of votes on bills before Congress, with points awarded for voting in line with what the ACU considers
to be the conservative position (i.e., a higher score is a more conservative score, and a missed vote neither raises
nor lowers a Member's rating). ACU ratings are on a scale of 1 to 100, with 100 being the most conservative score
possible.
