Professor Trahan received his J.D. with high honors from Louisiana State University in 1989, where he was the Articles Editor of the Law Review and a member of The Order of the Coif. Before joining the LSU Law Center faculty in 1995, he served as a law clerk to the late Judge Alvin B. Rubin of the United States Court of Appeals, Fifth Circuit, for one year and then practiced law with the firm Phelps Dunbar in Baton Rouge, Louisiana, for five years.

A "civil law" specialist, he presently teaches Persons & Family, Property, Security Devices, Successions & Donations, and Sales & Leases and has taught Western Legal Traditions, Obligations, and Matrimonial Regimes. He is co-author, with Professor Emeritus Kenneth Murchison, of Western Legal Traditions & Systems: Louisiana Impact, the textbook used in the Western Legal Traditions course at the LSU Law Center and co-author, with Professor Emeritus Katherine Spaht, of Family Law in Louisiana, the textbook used in most Family Law courses taught in the state.

He participates actively in law reform work, through the Louisiana State Law Institute, as the Reporter of the Birth Certificates Committee and as a member of the Persons Committee and a member of the Surrogacy Committee, and he regularly lectures on civil law topics at the "Recent Developments" seminars put on by the Louisiana Center of Continuing Professional Development.