Earlier in his career, Nathan served as a federal prosecutor, where he managed complex multi-agency state and federal investigations, conducted federal grand jury investigations, and first-chaired felony trials in U.S. District Court. He began his legal career on active duty with the U.S. Army Judge Advocate General's (JAG) Corps. In 2026, he retired from the Army Reserve as a Lieutenant Colonel.

Nathan's healthcare litigation experience includes disputes over payment and reimbursement, HIPAA, the Common Rule, breach of contract and certificate of need matters. He has defended hospitals, healthcare corporations, pharmaceutical companies and individuals in healthcare fraud investigations brought by federal and state agencies, and he has represented health systems in Department of Justice investigations involving the False Claims Act and the Americans with Disabilities Act. He also litigates constitutional and civil rights matters on behalf of state legislative bodies and political committees.