Henessy has experience representing clients in a variety of matters with particular focus on corporate governance and commercial investigations. During her time in law school, Henessy was a student attorney for the American University Washington College of Law (AUWCL) Civil Advocacy Clinic and argued before the District of Columbia Office of Administrative Hearings. She also served as a Senior Staffer for the AUWCL Law Review and the Executive Tournament Director of the AUWCL Moot Court Honor Society.