Mike Sundermeyer maintains a national trial practice with emphasis in professional liability defense, complex litigation, and administrative law. He has served as lead counsel in a variety of professional malpractice, real estate, securities, administrative, product liability, contract, partnership, and criminal defense matters. A member of the Bars of the District of Columbia, Maryland, Virginia, and of numerous federal courts, he has handled litigation that arose from or was filed in Arkansas, California, Delaware, the District of Columbia, Florida, Georgia, Illinois, Indiana, Kentucky, Maryland, Missouri, New Jersey, New York, Ohio, Oklahoma, Pennsylvania, Puerto Rico, Rhode Island, South Carolina, Texas, Utah, Virginia, West Virginia, and Wyoming. He has multi-year listings in Best Lawyers in America, Super Lawyers, and as one of "Washington's Top Lawyers" in Washingtonian Magazine.

Mr. Sundermeyer has defended major law firms in malpractice and other professional liability claims since 1979. His clients have included several Wall Street firms and numerous members of the Attorneys Liability Assurance Society. He also advises law firms on professional responsibility and liability prevention issues. He chairs the firm’s Ethics Committee.

In the field of administrative law, Mr. Sundermeyer has represented the Air Transport Association of America and major airlines.

Mr. Sundermeyer is a member of the Rules of Professional Conduct Review Committee of the D.C. Bar and of the Lawyers Committee of the National Center for State Courts.  He speaks at continuing legal education seminars and programs. He has served on the faculty of the Virginia State Bar Professionalism Course. Other lectures and programs include Federal Judicial Center Case Management Seminar for Federal Judges, Panel on Civil Litigation, 2011; "Legal Ethics Roundtable," Corporate Counsel Institute, Georgetown University, 2009; Georgetown University Law School Law Firm Roundtable, 2007-11; Panelist on Director and Officer Liability, Stanford University Law School Directors' College, 2005; "Attorney Liability in the Post-Enron, Sarbanes-Oxley Era," D.C. Bar Panel, 2005; "Practical Legal Ethics in Virginia 2004;" "Ethical Issues Encountered in Representing Financially Troubled Companies," ABA National Conference on Professional Responsibility, 2004; "Whistle Blowing in the Wind: Retaliatory Discharge of Lawyers Who Follow the Ethics Rules," ABA National Conference on Professional Responsibility, 2004; "Ethical Issues for Lawyers and Experts," 2004; and "Practical Legal Ethics in Virginia," 2003.