Catherine O’Sullivan

Catherine O’Sullivan graduated cum laude from Boston College with a major in Philosophy and minor in Management and Leadership. During college, she served as president of the National Alzheimer’s Buddies club and was a member of the club equestrian team. Prior to her senior year of college, she interned with the Volunteer Lawyers Project in Boston, working on housing and appellate matters and gaining early exposure to the impact of effective legal advocacy for individuals facing serious challenges.

Ms. O’Sullivan earned her Juris Doctor in 2024 from the University of Denver Sturm College of Law. While in law school, she served as an Articles Editor of the Denver Law Review, where she edited and reviewed articles submitted by scholars, law professors, and fellow students. She also authored a case comment, NY State Rifle & Pistol Ass’n v. Bruen: The Supreme Court’s Insensitivity to Sensitive Places, 101 DENV. L. REV. 215 (2024), which was one of a select number of student pieces chosen for publication—a distinction reflecting her commitment to careful legal analysis and scholarship.

Before her second year of law school, Ms. O’Sullivan honed her research and writing abilities by interning for Judge A. Bruce Jones of the Second Judicial District in Denver. She later worked with the Rocky Mountain Veterans Advocacy Project, advocating on behalf of veterans seeking disability benefits and discharge upgrades based on mental health considerations. During law school, she also volunteered in a Wills Lab, assisting individuals with estate planning documents.

Following graduation, Ms. O’Sullivan served as a law clerk to Justice Brian D. Boatright at the Colorado Supreme Court, Colorado’s highest appellate court. In that role, she strengthened her analytical research and writing skills by working through complex legal issues often involving several practice areas. She wrote certiorari and bench memoranda, assisted with opinion drafting, and observed numerous oral arguments. These experiences inform her approach to case strategy and advocacy.

During her clerkship, she volunteered regularly as a guest judge for We the People, a civic education program that hosts simulated congressional hearings for high school students. Ms. O’Sullivan currently volunteers as a mentor for Law School . . . Yes We Can, empowering underrepresented students to pursue law school and careers in the legal profession.

After her clerkship, Ms. O’Sullivan practiced at a respected asbestos litigation firm in the Philadelphia region. There, she prepared clients for depositions, attended mediations, drafted motions, and assisted attorneys with trial preparation, advocating on behalf of individuals harmed by exposure to asbestos-containing products.

Ms. O’Sullivan joined Block O’Toole & Murphy in January 2026. As an associate at the firm, she draws on a strong foundation in appellate and trial-oriented litigation, sharpened by her clerkship on Colorado’s highest court and subsequent experience in civil litigation. Her analytical rigor, persuasive legal writing, and commitment to thoughtful, client-first advocacy equip her to contribute meaningfully at every stage of the litigation process. Ms. O’Sullivan is dedicated to pursuing justice for individuals whose lives have been profoundly affected by serious injury and stands ready to serve clients with integrity, diligence, and compassion. Ms. O’Sullivan is admitted to practice law in Pennsylvania and Colorado.

Bar Admissions

• Pennsylvania
• Colorado

Education

• University of Denver Sturm College of Law – J.D.
• Boston College – B.A.
  • Major: Philosophy
  • Minor: Management and Leadership