He served in the United States marine Corps from 1971 - 1974, as a Judge Advocate General (JAG). After his discharge from the United States Marine Corps, he began his law career with the West Palm Beach law firm of Cone, Wagner, Nugent. In 1980, he formed the law firm of Easley, Massa & Willits, along with Attorneys H. Michael Easley and Richard H. Willits. In 1990, Mr. Massa formed the law firm of Patrick C. Massa, P.A., which has continued up to the present time. Mr. Massa's practice since 1974 has been primarily in the field of Plaintiffs' Personal Injury Litigation. In 1983, Mr. Massa became board certified as a specialist in Civil Trial Law, through the Florida Bar.

Mr. Massa has mediated approximately 3,000 cases since he was certified as a mediator in 1994. The mediations have involved disputes in both Federal and State Circuit Courts here in South Florida. The types of cases mediated include all types of civil matters, including torts, commercial disputes, contract disputes, employment law, probate litigation, and insurance coverage disputes. The tort mediations have included many multi-party malpractice cases, wrongful death cases, products liability cases, premises liability cases and insurance bad faith cases.