Father Guy Selvester who blogs at the Shouts in the Piazza, comments on people who fulfill their Sunday obligation when attending the late afternoon wedding of a friend. He quotes a Guide for Wedding Guests found on the Internet:
"If you are attending a Catholic nuptial wedding on a Saturday at 4 p.m. or later, you've just landed a twofer: It's a full Mass, and while it's sort of distracting (you are thinking about your friends getting married, and probably not as focused as usual on the words that the priest is saying) it still counts."
Then he comments: That's not entirely true and it does, in my opinion, play into one of the worst habits of American Catholics today. Namely, wanting to discover what the absolute minimum is that is required with regards to going to church. Too many Catholics are looking to get out of as much as they possibly can and only do that which is absolutely required. I doubt very much that too many Catholics will encounter a nuptial mass being celebrated after 4, PM on a Saturday anyway. My point is that while it may fulfill the absolute letter of the law that one attend mass each Sunday (and, of course we define Sunday as beginning at sundown on Saturday) attending a wedding as your Sunday mass hardly fulfills the spirit of the law. [snip] Read It All Here
I'd like to raise another legal issue. If 4:00 p.m. Saturday is "sundown" and thus legally Sunday in Canon Law, what is the legality of all those "Sunday" Masses that start after 4:00 p.m. on Sunday when it logically must be legally "Monday?"
Here in the Twin Cities I have a list of parishes that have Masses starting at 4:30, 5:00, 6:30, 7:00, 7:30 and 9:00.
Astronomically, today, maybe the longest day of the year, in our latitude the sun will be setting after 9:00 p.m. But on December 20, the shortest day of the year, I believe the sun sets betfore 5:00 p.m.