Born in Canton, China,[1] Seto received a Bachelor of Science in chemistry from Saint Louis University in 1962, and a Juris Doctor from the Saint Louis University School of Law in 1968.

[2] Seto was an assistant circuit attorney for the Felony Division of St. Louis, Missouri from 1968 to 1969, then became patent counsel to Monsanto Chemical Co. from 1969 to 1970, and deputy corporation counsel in the Division of Legal Memorandums and Opinions for the City and County of Honolulu, Hawaii, from 1970 to 1971.

[1] Seto was a senior patent litigation attorney for the United States International Trade Commission from 1976 to 1981.

He became a trial judge of the United States Court of Claims in 1981, and on October 1, 1982 he was elevated by operation of law to a new seat on the United States Court of Federal Claims authorized by 96 Stat.

[1] He resigned on June 20, 1987, to become an administrative judge for the Board of Contract Appeals of the United States Department of Agriculture, a position he held until 1998.