Judge Emmet G. Sullivan was born in Washington, D.C., and attended public schools in the District of Columbia until his graduation from McKinley High School in 1964. In 1968, he received a Bachelor of Arts Degree in Political Science from Howard University and, in 1971, a Juris Doctor Degree from the Howard University School of Law. Upon graduation from law school, Judge Sullivan was the recipient of a Reginald Heber Smith Fellowship and was assigned to the Neighborhood Legal Services Program in Washington, D.C. The following year, he served as a law clerk to Superior Court of the District of Columbia Judge James A. Washington, Jr., a former professor and Acting Dean of Howard University School of Law.
 
In 1973, Judge Sullivan joined the law firm of Houston & Gardner. He subsequently became a partner and was actively engaged in the general practice of law with that firm until August 1980, when his law partner, William C. Gardner, was appointed as an Associate Judge of the Superior Court of the District of Columbia. Thereafter, Judge Sullivan was a partner in the successor firm of Houston, Sullivan & Gardner. Over the years, ten lawyers from the Houston law firm went on to become judges.
 
While in private practice, Judge Sullivan was a member of a number of bar associations, and served on various court advisory and rules committees. He was admitted to practice law before the United States Supreme Court, the United States Court of Appeals for the District of Columbia Circuit, the United States District Court for the District of Columbia, the United States Court of Military Appeals, the United States Tax Court, and the District of Columbia Court of Appeals. He was a perennial voting delegate to the Circuit Judicial Conference and the District of Columbia Judicial Conference. He served on the Board of Directors of the District of Columbia Law Students in Court Program; the District of Columbia Judicial Conference Voluntary Arbitration Committee; the Nominating Committee of the Bar Association of the District of Columbia; and the U.S. District Court Committee on Grievances.
 
On October 3, 1984, Judge Sullivan was appointed by President Ronald Reagan to serve as an Associate Judge of the Superior Court of the District of Columbia. As an Associate Judge of the Superior Court, Judge Sullivan was one of only seven judges in the twenty-four year history of that court to have served full-time in every division. He served as the Deputy Presiding Judge and Presiding Judge of the Probate and Tax Divisions, as well as chairperson of the Rules Committee for those divisions. He was also a member of the Court Rules Committee and the Jury Plan Committee. Judge Sullivan has been featured as the Judge in two juror orientation movies – one shown to prospective jurors in Superior Court and another used by the Council for Court Excellence to educate students about their future responsibility as jurors – and in a training film for the Probation and Pretrial Services Divisions of the Administrative Office of the United States Courts.
 
On November 25, 1991, Judge Sullivan was appointed by President George H. W. Bush to serve as an Associate Judge of the District of Columbia Court of Appeals. While an Associate Judge of that court, and in addition to his full-time case management responsibilities, Judge Sullivan was Chairperson for the Nineteenth Annual Judicial Conference of the District of Columbia, which was held in 1994. The theme for the conference was “Rejuvenating Juvenile Justice - Responses to the Problems of Juvenile Violence in the District of Columbia.” Judge Sullivan was also appointed by Chief Judge Wagner to chair the “Task Force on Families and Violence for the District of Columbia Courts.”
 
On June 16, 1994, Judge Sullivan was appointed by President William J. Clinton to serve as United States District Judge for the District of Columbia. Upon his appointment as a United States District Judge, Judge Sullivan became the first person in the District of Columbia to have been appointed by three United States Presidents to three judicial positions.
 
Since his appointment to the federal court, Judge Sullivan has been appointed by four Chief Judges to serve on both the District of Columbia Judicial Disabilities and Tenure Commission and the District of Columbia Judicial Nomination Commission. Judge Sullivan served as Chair of the Judicial Nomination Commission from 2005 until 2022. The Judicial Nomination Commission recommends candidates to the President of the United States for judicial appointment to the Superior Court of the District of Columbia and the District of Columbia Court of Appeals and also appoints the Chief Judges for both courts. As Chair of the Judicial Nomination Commission, Judge Sullivan regularly testified before the Council of the District of Columbia. Judge Sullivan also chairs the United States District Court’s Interagency Detention Workgroup, which was created in 2000 to improve the coordination and logistical planning for detention related processes in the District of Columbia. From 1998 to 2005, Judge Sullivan served on the United States Judicial Conference Committee on Criminal Law, having been appointed to that position by Chief Justice William H. Rehnquist. Judge Sullivan chaired that committee’s Legislative Subcommittee and, in that capacity, he testified before Committees of the United States House of Representatives on behalf of the Judicial Conference. From 2012 to 2018, Judge Sullivan served on the Judicial Conference Space and Facilities Committee, having been appointed to that position by Chief Justice John G. Roberts, Jr.
 
Judge Sullivan has also served on the Dean Search Committee for the Howard University School of Law. His service on that committee culminated with the appointment of Kurt Schmoke, by former Howard University President H. Patrick Swygert, to serve as the Dean of the School of Law. Judge Sullivan is a former member of the Board of Directors and Executive Committee of the Council for Court Excellence and of the Frederick B. Abramson Memorial Foundation. He is currently a member of the Abramson Foundation’s Advisory Council. The Abramson Foundation awards annual financial scholarships and provides mentoring to District of Columbia public high school graduates attending four-year colleges and universities. Judge Sullivan is a frequent public speaker and panelist, and is also a regular guest speaker at a number of local public schools, colleges, and universities.

Judge Sullivan is the recipient of many honors, including the Ollie May Cooper Award awarded by the Washington Bar Association, the Thurgood Marshall Award of Excellence awarded by the Howard University Alumni Association, the Howard University Distinguished Alumni Award awarded by the President and Board of Trustees of Howard University, the American Inns of Court Professionalism Award for the District of Columbia Circuit for 2015, the National Bar Association’s Gertrude E. Rush Award, the Charles Hamilton Houston Medallion of Merit awarded by the Washington Bar Association,  Sigma Delta Tau Legal Fraternity’s Outstanding Service Award, American University’s Washington College of Law North Star Award, and was named Judge of the Year for 2017 by the Bar Association of the District of Columbia. He was also inducted into the Washington Bar Association Hall of Fame. Judge Sullivan has also been recognized for his achievements by the District of Columbia Public School System, the Judicial Administration Division of the American Bar Association, the District of Columbia Judicial Disabilities and Tenure Commission, and the District of Columbia Bar.  In 2019, Georgetown University awarded Judge Sullivan the degree of Doctor of Laws, Honoris Causa. 
 
Judge Sullivan has taught as an adjunct professor at the Howard University School of Law, the American University Washington College of Law, and has served as a member of the visiting faculty at Harvard Law School's Trial Advocacy Workshop. 

Judge Sullivan is a member of the Washington Bar Association, the District of Columbia Bar and the Bar Association of the District of Columbia.