Judge Gallagher's work on the Court received praise from many. Professor Brainerd Currie of Duke University Law School wrote that Justices Thomas Gallagher, Harlan Stone, Robert H. Jackson and Roger Traynor were "among the modern Justices whose work has contributed to the enlightenment and to the cause of justice and reason in the conflict of laws." (13 Stanford Law Review 719.) Judge Gallagher's opinions are regarded by many members of the Minnesota bar as notable for their clarity and brevity. Judge Gallagher also took pride in mentoring his law clerks to think and write clearly. His law clerks who later obtained prominence include Harry M. Walsh, Minnesota Revisor of Statutes, and Walter F. Mondale, Vice President of the United States. When the Court was in recess, Judge Gallagher served on Presidential Emergency Boards created by President Harry S. Truman to avert railway strikes. He served as President of the Minnesota Safety Council for seven years. In 1948, he was Chairman of the Minnesota Branch of the National Conference of Christians and Jews. He was active in the American Legion, serving as Commander of Downtown Post 335, and as Judge Advocate for its Fifth District. Each year, he conducted panels for Legion-sponsored "Boys' State," in which he outlined for the young delegates the structure, procedure and jurisdiction of the state and federal courts. In 1962, he served as President of the University of Minnesota Law School Alumni Association.