Ben Cardin of Maryland gave an emotional opening statement, recalling the segregation and anti-Semitism of his childhood in Baltimore. He invoked Brown v. Board of Education, which outlawed segregation in schools, and Loving v. Virginia, which outlawed prohibitions on interracial marriage--both the kind of decisions that conservatives at the time described as "activist."
The lead up to the for hearings suggested race would play a tremendous role in the hearings--but Cardin's testimony is the first effort I've seen to put conservative complaints about "activism" and race in context--recalling that it was the "activist" decisions of the past that secured the kind of equal opportunities the Constitution once reserved only for white men. He also expressed concern that these protections, now established precedent, are in danger of judicial activism from the right.
All in all, it was among the most effective rebuttals to conservative complaints about Sotomayor and "activism" particularly given the emotion vocalized by the usually stoic Cardin.
UPDATE: Sheldon Whitehouse, who offered another excellent rebuttal, citing Jeffrey Toobin on Justice Roberts, and noting that "For all the talk of “modesty” and “restraint,” the right wing Justices of the Court have a striking record of ignoring precedent, overturning congressional statutes, limiting constitutional protections, and discovering new constitutional rights"
-- A. Serwer