In response to the attack on Solicitor General Elena Kagan's qualifications, we've demonstrated that at least 38 of the 111 justices to have served on the Supreme Court had no judicial experience at the time they were first nominated to the Court and that Kagan's experience is comparable to that of recent conservative justices, including William Rehnquist, John Roberts, and Clarence Thomas. Here's another important fact to consider. Seven of the nine Supreme Court justices who decided Brown v. Board of Education had no prior judicial experience.
The nine justices who unanimously overruled Plessy v. Ferguson and declared that school segregation was unconstitutional were Earl Warren, Hugo Black, Stanley Reed, Felix Frankfurter, William O. Douglas, Robert Jackson, Harold Burton, Sherman Minton, and Tom Clark. Of them, only Minton and Black had been judges before their Supreme Court nomination, and Black's judicial experience consisted of service as a Birmingham, AL police court judge from 1910-1911.