Last Sunday, Sept. 18, the annual Red Mass took place at Holy Cross Cathedral in Boston's South End. The Red Mass is an annual ritual for judges, lawyers, public officials, law professors and students to ask for the Holy Spirit's guidance in seeking justice. It is usually held at the beginning of the judicial year. (There's one in Washington, D.C., attended by U.S. Supreme Court Justices and others, celebrated before the beginning of the court's term in October.)

The tradition dates back to the high Middle Ages. Red is the liturgical color of the Holy Spirit, representing the seeming flames of fire that descended upon Mary and the apostles at the first Pentecost in Jerusalem. And so Cardinal Seán and the concelebrating priests wore red priestly vestments. In England during the Middle Ages, the judges of King's Bench in Westminster also wore red judicial robes, and doctors of law also wore red robes or academic hoods.

Now, of course, judicial robes are black; and most academic gowns are black as well. Priests, too, normally wear black. Liturgical texts are normally printed in black and white, though there are often red "rubrics" to provide instructions on what to do next, and often altar Missals have red covers.

The first part of every Mass, the Liturgy of the Word, involves readings from the Bible and preaching and prayers from the priest, a textual exercise in black and white. Catholics and non-Catholics alike can join in hearing and reflecting on God's Word and its relevance to their responsibilities in the legal profession to serve the common good through justice.

White is also a color associated with the pope, who uses a white cassock. Every Roman Catholic Mass involves prayer for, and communion with, the successor of St. Peter who is bishop of Rome. (White smoke from the Sistine Chapel also betokens the election of a new pope.) He is called "Holiness," because his office and duty is to impart holiness, just as judges on the Supreme Court are called "Justice" because it is their sworn duty to do justice.

The presence of different races and ethnic groups in the Catholic Church is also a reminder that Catholic means universal. It's black and white and red all over, and brown and Irish and Italian and Polish and Portuguese and Haitian and Nigerian and Latino and Filipino, and virtually every other ethnic and racial group.

Different shades of red still mark the clerical offices of bishop and cardinal. Red, of course, is also the liturgical color associated with martyrdom, giving witness to the truth to the point of shedding blood. Blood is red, and the shedding of blood involves sacrifice. Every Mass, in the liturgy of the Eucharist, involves a re-enactment in an unbloody way of the sacrifice of Jesus on the cross for love of us that was first accomplished on Calvary in a bloody manner. St. Thomas More, chief judicial officer in England under Henry VIII, and patron saint of statesmen and lawyers, gave his life rather than betray the truth of his conscience.

With such a rich history teeming with religious significance, why would a non-Catholic attend a Red Mass? After all, non-Catholics do not necessarily share our understanding of the pope's authority, or the Mass as a prolongation in space and time of Jesus' sacrifice on the cross, nor accept the Trinitarian belief in the Holy Spirit, nor even the divinity of Jesus, nor want to be reminded of duties they don't necessarily recognize. Justice Ruth Bader Ginsburg, for example, reportedly no longer attends the Red Mass in Washington because she doesn't want to be hectored about abortion.

It's a free country, of course, and that is her unquestioned right. But it is also possible to approach the Red Mass as an ecumenical occasion, to pray together that justice be done with wisdom and mercy, and to honor our rich heritage of religious freedom as Americans, which doesn't just mean freedom from religion, but freedom to freely exercise religion. Ex-mayor of New York City Ed Koch, for example, who is Jewish, went to St. Patrick's Cathedral to light a candle and pray and grieve in the wake of the attacks of 9/11.

Our own John Adams, as representative of the Massachusetts delegation to the Continental Congress, on one occasion in 1774 went to St. Mary's Catholic Church in Philadelphia, and reported to his wife Abigail:

"This afternoon, led by curiosity and good company, I strolled away to mother Church, or rather grandmother Church. I mean the Romish chapel. I heard a good, short moral essay upon the duty of parents to their children, founded in justice and charity, to take care of their interests, temporal and spiritual. ...The dress of the priest was rich white lace. His pulpit was velvet and gold. The altar-piece was very rich, little images and crucifixes about; wax candles lighted up. But how shall I describe the picture of our Saviour in a frame of marble over the altar, at full length, upon the cross in the agonies, and the blood dropping and streaming from his wounds! The music, consisting of an organ and a choir of singers, went all the afternoon except sermon time, and the assembly chanted most sweetly and exquisitely.

"Here is everything which can lay hold of the eye, ear, and imagination -- everything which can charm and bewitch the simple and ignorant. I wonder how Luther ever broke the spell. Adieu." Of course, I would add that the appeal is not just to the simple and ignorant. Even somewhat complicated and relatively knowledgeable people, like lawyers and law professors, can also be "charmed."

Dwight G. Duncan is professor at UMass School of Law Dartmouth. He holds degrees in both civil and canon law.