Terence J. Shannon obtained a Juris Doctor Degree from the University of California, Hastings College of Law. He began the practice of law in1974, working with George T. Davis the attorney who represented the Krupps in the Nuremberg Trials.
In April, 1975, he began working as Senior Attorney, in the Office of the Public Defender, City and County of San Francisco.
In April, 1979, he opened the practice of law, in San Mateo County.