Q: I am being asked around the office if attending an afternoon Mass on Sunday December 24 satisfies the obligation for both Sunday and Christmas Day. I don’t think so but my questioners (regular Mass attendees) have requested an answer from a higher authority.
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A: The USCCB’s Committee on Divine Worship answered this in its February 2017 Newsletter: “The prevailing view among many canon lawyers is that each obligation must be fulfilled with a separate Mass.” However, it notes this minority opinion: “Some canonists suggest that, in the absence of a definitive interpretation by the Holy See, attendance at the evening Mass shared by the two holy days is indeed sufficient to fulfill both obligations, based on the principle that in cases of doubt, laws are to be interpreted broadly.” As the Newsletter says, it would be hoped that Catholics foster a love for the Mass and desire to celebrate the holy days as fully as possible.