About David William
David William Casazza built his academic foundation around history and languages before turning to law. He earned a Bachelor of Arts in history and German language and culture from Princeton University and completed a Master of Arts in history at Johns Hopkins University in 2010. He later attended Harvard Law School, where he received his Juris Doctor.
Casazza's early legal career included two federal clerkships that shaped his interest in appellate work. In 2015 he served as a law clerk to a judge on the United States Court of Appeals. He went on to clerk at the Supreme Court of the United States in 2018. Those experiences exposed him to high-stakes legal briefing and the mechanics of judicial decision-making at the federal level.
Between and after his clerkships, Casazza joined Gibson, Dunn & Crutcher LLP as an associate. Records show he held associate positions at the firm beginning in 2016 and again in 2019. His time at the firm has involved work typical of large litigation practices: drafting briefs, preparing appellate arguments, and assisting on federal matters. The combination of appellate clerkships and experience at a national firm has informed the sort of litigation matters he handles.
Casazza is a member of the New York State Bar and the District of Columbia Bar. Those memberships reflect his professional ties to both jurisdictions. He is based out of an office on Connecticut Avenue in Washington, D.C., an address associated with firm work in the federal capital.
Colleagues and judges who worked with him during clerkships and at the firm have noted his familiarity with appellate procedure and federal litigation practice. He has experience preparing filings for appeals and for courts that review administrative and constitutional issues. That background has made appellate and Supreme Court-related litigation a recurring element of his résumé.
As of 2026 he continues to work in a practice that draws on his clerkship background and firm experience. His current practice centers on appellate litigation and matters that may reach the Supreme Court.
