Suppose you are a Justice.
Suppose I am the attorney representing a jurisdiction that bans Sunday sales.
Suppose I asserted that banning sales one day a week serves the secular societal purpose of causing the drunks who are unable to plan ahead and buy in advance on Saturday (ie, the worst ones) to dry out and either see the error of their ways or to seek the help that they clearly need due to symptoms withdrawal.
To simplify things, I'll concede that the secular societal purpose outlined above is more-or-less a ruse to justify the law if you'll concede that it IS at least a potential rational purpose for the law.
How would you, Justice @betarhoalphadelta distinguish between a rational purpose being used as a ruse and a rational purpose that is ACTUALLY the reason for the law?
It's a good question, and I'm not a lawyer or a SCOTUS justice.
I'd probably look at a lot of things.
I'd probably ask the attorney why it is on Sunday, i.e. why not Saturday, or Friday, or Tuesday? If you're that hardcore of a drunk, not being able to buy on Tuesday is just as impactful as not being able to buy on Tuesday. But it's less of a PITA for someone running a Sunday backyard BBQ or someone who ran out of beer at the Super Bowl party.
I'd probably look at the statements of the legislators that sponsored the law to see what statements were made by them around the time that it was passed. It's difficult to determine intent in a legal sense, even when
we all know what the real intent was. But sometimes if they say it out loud, you can identify that it was more about religion than public purpose.
And ultimately whether I would find it unconstitutional is unclear. As a non-lawyer and non-SCOTUS justice I think it's utter BS, but the law can often be tricky on these sorts of things.