I have 2 questions.
First, does any part of Canon law address Sunday worship and rest?
Second, regarding a friend who keeps his fish market open on Sundays for business, is that a sin against the 3rd commandment because it is unnecessary work? He keeps the shop open 7 days a week but goes to Mass on Sundays.
Answer by Rev. Mark J. Gantley, JCL on 10/21/2007:
Canon 1247 states: "On Sundays and other holy days of obligation, the faithful are obliged to participate in the Mass. Moreover, they are to abstain from those works and affairs which hinder the worship to be rendered to God, the joy proper to the Lord's Day, or the suitable relaxation of mind and body."
I would recommend that you read the 1998 Apostolic Letter of Pope John Paul II Dies Domini: http://www.vatican.va/holy_father/john_paul_ii/apost_letters/documents/hf_jp- ii_apl_05071998_dies-domini_en.html