Professor Thomas P. Gallanis is an internationally renowned expert on trust, succession, property, and fiduciary law.  He is particularly interested in their comparative and cross-border aspects.  He is also a prize-winning legal historian with expertise in English and European legal history.

He is an elected member of the International Academy of Estate and Trust Law, the American College of Trust and Estate Counsel, and the American Law Institute.

He has held prestigious visiting professorships and fellowships in the U.S. and overseas.  These include a visiting professorship at the University of Chicago, the Verner F. Chaffin visiting professorship at the University of Georgia, a full-year visiting fellowship at All Souls College in Oxford, a full-year Mellon fellowship at the Institute for Advanced Study in Princeton, the Herbert Smith Freehills visitorship in the law faculty of Cambridge University, and a visiting fellowship at the University of St. Andrews in Scotland.

He has also given named lectures in the U.S. and overseas, most recently the 2019 Amakasu Lectures on Trust Law in Tokyo.

Based on his international standing, he served on the Law panel for the Hong Kong Research Assessment Exercise 2020.

His scholarly articles have been published in peer-reviewed journals in the United States, England, France, China, and Japan as well as in U.S. law reviews.

He is co-author of treatises on Wills, Trusts, and Estates (6th ed., with Kurtz and English) and The Law of Property (6th ed., with Kurtz and English) and The Law of Property (6th ed., with Hovenkamp and Kurtz). He is also the author or co-author of prominent casebooks: Family Property Law: Cases and Materials on Wills, Trusts, and Estates (8th ed. 2020) and Fundamentals of Property Law (5th ed. 2020, with Burke and Burkhart).

He is active in law reform through the Uniform Law Commission and the American Law Institute.

Within the Uniform Law Commission, he is the executive director of the Joint Editorial Board for Uniform Trust and Estate Acts, which is the official oversight body for all uniform laws in the field of trusts and succession.  He was the reporter (principal drafter) of the Uniform Powers of Appointment Act and the Uniform Real Property Transfer on Death Act.

Within the American Law Institute, he served as associate reporter for the Restatement Third of Trusts and currently serves as an adviser to the Restatement Fourth of Property.

He is also active as a legal historian.  He was awarded the Selden Society's David Yale Prize for his scholarly article on the history of evidence law in English courts, which was judged "a distinguished contribution to the history of the laws and legal institutions of England and Wales."

With an international team of scholars, he published The Oxford Edition of Blackstone: Commentaries on the Laws of England with Oxford University Press.

He is preparing, for publication by the Selden Society, a scholarly edition of the judicial notes of Sir Dudley Ryder, who served as Chief Justice of the Court of King's Bench.

He is a member of the editorial boards of the Journal of Legal History and Continuity and Change and the Brill series on Studies in the History of Private Law.