He was in the United States Army Reserve as a Captain in the JAG Corps from 1957 to 1964.

[2] O'Conor was nominated by President Gerald Ford on March 17, 1975, to a seat on the United States District Court for the Southern District of Texas vacated by Judge Ben Clarkson Connally.

[2] After his resignation from the federal bench, O'Conor returned to the private practice of law in Houston, Texas.

[2] He remained active with law firm FedArb, which provides alternative dispute resolution in complex commercial cases.

[3] In addition to his service with FedArb, he also maintained a private law practice with his wife, Helen D.