Kennedy was predictably nasty and inaccurate. His main substantive attack was on Roberts’s view (early in the Reagan administration) that Section 2 of the Voting Rights Act should NOT ban election practices that simply have a disproportionate impact on the basis of race, when the practice is adopted without discriminatory intent, is racially neutral, and is applied nondiscriminatorily. The classic example is an at-large city council system where blacks are a sizeable minority (so that they may never be able to elect a member). The Supreme Court said in Mobile v. Bolden in 1980—where the issue was such a city council system–that such a practice is not illegal unless it was adopted with discriminatory intent; Congress overturned this decision when it amended the Voting Rights Act in 1982.
Remember how Kennedy kept saying that “Zimmer was the law of the land” until the Mobile case? Well, Zimmer was a court of appeals, not a Supreme Court, decision, so Kennedy was wrong. (See footnote 16 of Justice Stewart’s opinion in Mobile.)
Kennedy also seemed to think that, since Roberts thought it was okay for the Court to consider the bad effects of segregation in Brown, it ought to be okay to consider only disproportionate results in the voting context. But it was the bad effects of deliberate segregation that the Court cited in Brown; the whole issue in the voting context was whether disproportionate results that are NOT the result of actual discrimination ought to be illegal.
BTW, the lawyer who argued the Mobile case for the government once told me that, after the Supreme Court handed down the Mobile decision, the plaintiffs were able to prove that the city’s adoption of the at-large system was racially motivated, so they won anyway—proving that it is not the case that an intent requirement is impossible to meet.