Foley said he never regretted the decision - assisted by his voluntary teaching of religious studies to special education students - but that he sees many similarities between his work and the legal profession.
"We both seek to challenge people to recognize their dignity and to live according to it," he said. "We both consider law as a guide to a well ordered society. We both see law as a means in which people can be educated to perceive what is good and to strive for it."
Four of the five Roman Catholics on the high court - Chief Justice John Roberts and Justices Antonin Scalia, Anthony Kennedy and Clarence Thomas - came to worship at the Cathedral of St. Matthew the Apostle; the fifth, Justice Samuel Alito, did not attend. They were joined by Justice Stephen Breyer, who is Jewish.
The cardinal also related a story of a visit from Scalia and his wife, Maureen. Foley said he explained the legal subject of his dissertation to the justice, who disagreed with his theories.
According to Foley, the argument ended when Scalia's wife said, "Oh, admit it Nino, the archbishop is right."
In his remarks, Foley expressed a wish that "all of us may see law as a reflection of God's loving care." He went on to pray for those doing the "extremely important work of formulating and applying law."
The Red Mass long has been held at the cathedral by the John Carroll Society, a group of Washington professionals who are Catholic.
The name of the service, which dates back centuries and is conducted to ask for guidance for those who seek justice, comes from the red vestments worn by the celebrants. The service traditionally is held the day before the Supreme Court's new term.