December 8 is usually the Solemnity of the Immaculate Conception of the Blessed Virgin Mary, the patronal feast day of the United States. Because it’s such an important feast for the U.S. church, it is the only holy day of obligation in the U.S. that remains a holy day of obligation even if December 8 falls on a Saturday or Monday.
But what happen when December 8 is a Sunday, as it is in 2013?
In the Table of Liturgical Days, which you’ll find at the end of the Universal Norms on the Liturgical Year and the Calendar (see the front of your Roman Missal), Sundays of Advent rank higher than any other Solemnities. According to #5 of the Norms on the Liturgical Year, those Solemnities then get moved to the next Monday.
So in 2013, Monday, December 9 is the Solemnity of the Immaculate Conception, right? Right! And, because it’s our national feast day, it’s a holy day of obligation, right? Not quite.
According to the United States Conference of Catholic Bishops, the obligation is attached to the calendar date, not to the transferred feast. So December 8 remains a holy day of obligation, which just also happens to be Sunday, the “primordial feast day” (Universal Norms on the Liturgical Year and Calendar, 4), or as it said in the previous translation of that document, “Sunday must be ranked as the first holyday of all.”
But, still, you know it’s good to participate in Mass on December 9, even if it’s not a holy day of obligation.
Image: La Inmaculada concepción de los Venerables o de Soult, Bartolomé Esteban Murillo, 1678, public domain