About Mark
Mark O’Brien is an attorney with Copenbarger & Copenbarger, LLP. He brings more than a decade of experience in estate planning, trust and estate administration, probate, conservatorships, and trust and estate litigation, having worked extensively in both attorney and senior paralegal roles throughout Southern California.
Mark works closely with clients and legal teams to support comprehensive estate and wealth planning solutions, including business succession planning, tax-efficient transfer strategies, and generational wealth preservation. His background includes significant hands-on experience managing complex trust administrations, probate matters, fiduciary accountings, and contested trust and probate proceedings.
Mark is known for his practical, detail-oriented approach and his ability to guide clients through complex legal processes with clarity and confidence. He values collaboration and is committed to helping clients protect their families, assets, and long-term goals.
Personal
In his free time, Mark enjoys spending time with his wife and son, attending hockey games, exercising, and traveling.
Awards
- 2024 Super Lawyers – Rising Star
- Juris Doctorate, cum laude
- 7x CALI Award recipient (Excellence for the Future Awards)
Practice Areas / Responsibilities
Mark supports the firm’s Estate Planning, Trust Administration, Probate, and Conservatorship departments, with responsibilities that include:
- Estate and trust administration
- Probate matters
- Conservatorships and guardianships
- Fiduciary accountings
- Estate, gift, and tax planning support
- Business succession and wealth transfer planning
- Trust and probate litigation support
Professional Qualifications
- Juris Doctor – University of La Verne, College of Law [ABA portion]
- Graduate Certificate – Taxation; University of California, Los Angeles
- Bachelor’s Degree – Finance, Real Estate, and Business Law; Cal Poly Pomona
- Member, State Bar of California
- Member, Orange County Bar Association
- Section Member, Trusts and Estates
- Section Member, Young Lawyers Division
- Member, Los Angeles County Bar Association
