Born in Memphis, Tennessee, Marshall earned a Bachelor of Arts degree in 1985 from Arkansas State University, where he was a member of Tau Kappa Epsilon fraternity, and a Master of Science degree in 1987 from the London School of Economics.

[1][3] From 1989 until 1991, Marshall served as a law clerk for Judge Richard S. Arnold on the United States Court of Appeals for the Eighth Circuit.

[1][3] After Barack Obama was elected president, Marshall interviewed with Arkansas Senator Blanche Lincoln about a vacant federal district court slot on December 29, 2008.

On March 12, 2009, Lincoln and Arkansas Senator Mark Pryor told Marshall that he and others would be recommended to the White House for consideration.

On December 3, 2009, Obama formally nominated Marshall to the seat, to replace Judge Billy Roy Wilson, who assumed senior status in October 2008.