The Honorable Mary Miller Johnston was appointed to the Superior Court of Delaware on September 25, 2003.

Judge Johnston received her J.D. cum laude from Washington & Lee University School of Law where she served as Lead Article's Editor of the Law Review. She also has a B.A. magna cum laude in music from Wittenberg University, and an M.A. in music from Northwestern University.

Before coming to the bench, Judge Johnston served as Chief Counsel of the Delaware Supreme Court's Office of Disciplinary Counsel, prosecuting attorney discipline cases and unauthorized practice of law matters. She formerly was a partner with Morris James, LLP practicing primarily in the areas of corporate and commercial litigation. She currently is assigned as a member of the Court's Complex Commercial Litigation Division.

Judge Johnston is past chair of the Delaware State Bar Association's Women and the Law Section; a recipient of the Bar Association's Women's Leadership Award; and was a member of the Pro Se Litigation Assistance Committee. She is a member of the Delaware Supreme Court's Permanent Advisory Committee on the Delaware Lawyers' Rules of Professional Conduct, the Professionalism Committee, the Court's Commission on Continuing Legal Education, and the Richard S. Rodney Inn of Court. Her past service includes the Judicial Ethics Advisory Committee and Judicial Liaison to the Executive Committee of the Delaware State Bar Association. Judge Johnston serves as a member of the Washington & Lee School of Law Council and member of the Board of Governors of Wesley Theological Seminary. She is past president of the Board of Children & Families First.

Judge Johnston's present term ends October 28, 2027.