Political ideology and race in judicial decision making

To study the role that political ideology and race plays in judicial decision-making, Cox and Miles examine all the cases decided under Section 2 of the Voting Right Act of 1965. This section applied a prohibition against the denial or abridgment of the right to vote on the basis of race, color, or membership in a protected language group as well as literacy tests on a nationwide basis. In 1980 the Supreme Court held that the 15th amendment proscribed only intentional racial discrimination in voting and affirmed that Section 2 was indeed only a restatement of this amendment. In response, Congress amended the Section 2 to eliminate the requirement that plaintiffs show purposeful discrimination and instead the plaintiff must show that “based on the totality of circumstances, . . . the political processes leading to nomination or election in the State or political subdivision are not equally open to participation” by members of a protected group.
They find significant influence of ideology. Democratic appointees are significantly more likely than Republican appointees to cast a vote in favor of liability under section 2 of VRA and this effect become more prominent when judges appointed by the same president sit together on panels. The first influence is called “party effect” or “ideology effect” while the second one is called “panel effect”. They find even a stronger effect from the race of judges than their political affiliations on their voting behavior.