BRAINTREE -- Continuing a tradition dating back to the Middle Ages, attorneys, judges, and others associated with the legal profession in Massachusetts will attend the Celebration of the Red Mass on Sept. 18, sponsored by the Catholic Lawyers Guild of Boston.

Cardinal Seán P. O'Malley will be the principal celebrant at the 11:30 a.m. Mass at the Cathedral of the Holy Cross. Afterwards a luncheon -- featuring keynote speaker Chief Justice Phillip Rapoza of the Massachusetts Appeals Court -- will be held at the Seaport Hotel in Boston.

The first "Red Mass" was celebrated at the Cathedral of Paris in 1245. The term refers to the red vestments traditionally worn by clergy to represent the Holy Spirit. The Mass is held to invoke the power of the Holy Spirit in guiding members of the legal profession, before the beginning of the judicial year.

Father Mark O'Connell, judicial vicar of the archdiocese and spiritual director for the Catholic Lawyers Guild, said he hopes that attendees will be built up by two "solid messages," one from the cardinal and the other from Rapoza.

Rapoza spent his undergraduate years at Yale College, and received his law degree from Cornell. Before becoming the chief justice of the Massachusetts Appeals Court in 2006, he spent time in private practice, as an assistant district attorney and as an Associate Justice of the Massachusetts Superior Court.

"He's not only a scholar (and) a highly esteemed member of the judiciary, but he's a man who walks his talk, he gives back," said Maura Doyle, co-vice president of the Catholic Lawyers Guild.

Doyle said this was especially evidenced by Rapoza's time serving in East Timor on a war crimes tribunal. Rapoza went on an unpaid leave of absence to serve as the chief international judge on the Special Panels for Serious Crimes in East Timor, a U.N. founded group, from 2003-2005.

Paul McNamara, co-vice president of the Catholic Lawyers Guild, is looking forward to hearing Rapoza speak since he has acted on the Church's social justice teaching.

"I think that that's important, especially for young lawyers, to understand that the social justice aspect of the teaching of the Church is something that you can use in your everyday practice," said McNamara.

Doyle said she would love to see a wider range of people attend the Red Mass. This would include legislators and members of the executive branch, or "anyone involved in the administration of justice."

Father O'Connell would also like law students to attend the Red Mass events and for people to find out more about the guild. The group hosts other events and has a mentoring program between older and younger Catholic lawyers.

More information on The Catholic Lawyers Guild and the Red Mass is available at the guild's web site, www.clgb.org.