Professor Marcus began his legal career in Canada, where he worked as a litigator in private practice and for the Canadian government on constitutional policy issues. After moving to Washington, D.C., he practiced at Covington & Burling, and was later a partner at Baach Robinson & Lewis (now Lewis Baach). In 2004, Professor Marcus formed his own litigation and counseling firm. He represents clients in business, real estate and partnership disputes, lawyers and law firms on legal ethics issues, and charter schools on all aspects of their operations. His cases have included veil piercing, the False Claims Act, trade secrets, corporate governance, enforcement of judgments, professional malpractice, adverse possession, right-of-first refusal, restrictive covenants, broker commissions, property mismanagement, construction defects, breach of fiduciary duties, minority shareholder rights, fraudulent conveyances, and charter school funding and closure litigation. Professor Marcus previously taught Canadian Law and Legal Institutions at Georgetown University Law Center and at the Trial Advocacy Workshop at Harvard Law School. He is a member of the D.C. Bar Rules of Professional Conduct Review Committee.