The first Monday in October marked the beginning of Clarence Thomas's third decade on the U.S. Supreme Court. When the Court accepted a challenge to the Voting Rights Act of 1965 last week, the current term also became Thomas's best chance for leaving a lasting legacy on American law.

To date, Thomas's powerful voice has been heard almost exclusively through his concurring and dissenting opinions rather than in opinions for the Court. But that may change this term with two landmark cases.

One is Shelby County v. Holder, the dispute over Congress' decision in 2006 to reauthorize Section 5 of the Voting Rights Act -- the provision that requires many state and local governments, mostly in the South, to obtain permission from the Justice Department or a federal judge before making changes that affect voting. The second is Fisher v. University of Texas, the pending challenge to the use of race in college admissions decisions. With these two cases, the nation's highest ranking African American jurist has been provided with an unprecedented opportunity to commit the Court to the notion of color-blind constitutionalism for which he has been working for most of his professional life.

Earl Warren wrote in his memoirs that the voting rights cases -- not Brown v. Board of Education and its progeny -- were the most important cases decided during his time as chief justice. He believed that once African Americans were allowed to participate freely and fairly in the electoral process, they no longer would need to look to the judiciary for help.

The voting rights cases are also central to Thomas's Supreme Court tenure. His "breakthrough" opinion is often said to be his 1994 concurring opinion in Holder v. Hall, in which he called for a dramatic rethinking of the Court's voting rights jurisprudence. Thomas wrote that racial groups shouldn't "be conceived of largely as political interest groups," that African Americans don't all think alike, and that existing case law should be overturned to eliminate claims for "proportional allocation of political power according to race." As far as the Voting Rights Act itself is concerned, he concluded, "an 'effective' vote is merely one that has been cast and fairly counted."

Thomas's recent Voting Rights Act opinions and votes are consistent with his opinion in Holder v. Hall. For example, in 2009's Northwest Austin Municipal Utility District Number One v. Holder, he again wrote separately, this time to explain why the Court's choice to decide the case on statutory rather than constitutional grounds was inappropriate. In his judgment, "lack of current evidence of intentional discrimination with respect to voting renders [Section 5 of the Voting Rights Act] unconstitutional."

With respect to affirmative action, the issue with which Thomas is most closely associated, many Court watchers were surprised that the justices agreed to review the University of Texas's undergraduate admissions program so soon after upholding a similar plan devised by the University of Michigan Law School. It seems likely that the Court took the Texas case to overrule the Michigan case. If the justices do overrule it, Thomas could well pen the majority opinion. After all, his separate opinions in this area are his most powerful opinions. To mention but the most recent -- his concurring opinion in the 2007 Seattle/Louisville race-based public school case -- he wrote: "The dissent attempts to marginalize the notion of a color-blind Constitution by consigning it to me and Members of today's plurality. But I am quite comfortable in the company I keep. My view of the Constitution is Justice Harlan's view in Plessy: 'Our Constitution is color-blind, and neither knows nor tolerates classes among citizens.' "

Edgar Fiedler famously warned that "He who lives by the crystal ball soon learns to eat ground glass." But it would be naive to ignore that a very conservative Court has agreed to decide both Fisher v. University of Texas and Shelby County v. Holder during the current term. If the justices end racial preferences in admissions and scrap Section 5 (and I expect they will), and if Thomas writes one or both of the majority opinions (and I expect he will), Thomas will have cemented his legacy by ensuring that each American, no matter the color of his skin, is treated as an individual and not as a member of a racial or ethnic group.

Scott Douglas Gerber is a law professor at Ohio Northern University, and the author of "First Principles: The Jurisprudence of Clarence Thomas."