Blue Law
A blue law, in the United States and Canada, is a type of law designed to enforce moral standards, particularly the observance of Sunday as a day of worship or rest. Most have been repealed, declared unconstitutional or are simply unenforced, although prohibitions on the sale of alcoholic beverages, and occasionally almost all commerce, on Sundays are still enforced in many areas. This puzzles many non-Americans, given the supposed separation of church and state. Blue laws often prohibit an activity only during certain hours and there are usually exceptions to the prohibition of commerce, like grocery and drug stores. In some places blue laws may be enforced due to religious principles, but others are retained as a matter of tradition or out of convenience.