[1] He served as a Sergeant in the United States Army from 1944 to 1946 and after his discharge became a vocational advisor and psychometriest with the Veterans Administration in San Juan, Puerto Rico from 1946 to 1947.

He was a trial examiner for the Puerto Rico Labor Relations Board in San Juan in 1948.

He was Chief of the Legal Division of the Puerto Rico Labor Relations Board in San Juan from 1949 to 1952.

[2] In 1966, the United States Congress passed an act reorganizing the United States District Court for the District of Puerto Rico as an Article III court, with the judges thereof having life tenure and salary protection.

[2] After his resignation from the federal bench, Cancio engaged in the private practice of law.