During that period of active duty, Brown held positions as platoon leader for a target acquisition, reconnaissance and surveillance platoon, executive officer of a general support aviation company, a battalion logistics officer, and the flight operations officer for Task Force 23. After completing his active duty service, Brown returned to graduate school, entering Harvard Law School in 1989 and earning his JD degree. He attended Harvard Law School at the same time as future President Barack Obama, Artur Davis and actor Hill Harper. Brown was a member of the Board of Student Advisers. His third-year paper, written under the supervision of Professor Charles Ogletree, analyzed the scope of the Fourth Amendment's protections against unreasonable search and seizure in the military. Brown was Chair of the Membership Committee of the Black Law Students Association. Brown graduated from Harvard Law, with a Juris Doctor in 1992. After graduating from law school, Brown completed a two-year clerkship for Chief Judge Eugene Sullivan of the United States Court of Appeals for the Armed Forces. In 1994, he joined the Washington, D.C. office of the international law firm of Wilmer Cutler Pickering (now WilmerHale). Brown practiced law with the late John Payton, a renowned civil rights attorney and former president of the NAACP Legal Defense Fund, and Stephen H. Sachs, who was the United States Attorney for the District of Maryland from 1967 to 1970 and was the 40th Attorney General of Maryland. In 1998, Brown received Wilmer's Pro Bono Publico Award for his work in representing indigent clients. In 1999, Brown worked for Merrill Lynch for five months. Brown joined the Prince George's County land use and zoning law firm Gibbs & Haller in 2000, after having been elected to the Maryland General Assembly. Brown continued his military service as a Judge Advocate General (JAG) in the United States Army Reserve. Brown began his service as a JAG with the 10th LSO in Upper Marlboro, Maryland, where he held numerous assignments, including in the areas of international law and claims law. Brown ultimately attained the rank of Colonel in the U.S. Army Reserve before reaching the point of mandatory retirement in July 2014. His assignments included Commander of the 153rd Legal Support Organization in Norristown, Pennsylvania, where, in addition to supporting deploying service members and their families with legal services, he mobilized eighteen soldiers to Fort Hood, Texas in support of the III Corps' mission to Iraq. Prior to his tenure with the 153rd LSO, Brown was the Staff Judge Advocate for the 353rd Civil Affairs Command headquartered at Fort Wadsworth, New York.