Legal Question in Business Law in Washington

If you mean a law that prohibits retailers from checking your receipt on the way out the door, there is no such law. Any retailer can check you on the way out the door to ensure that what you leave with is what you paid for. The fact that they do this will every single customer is a way for them to avoid discrimination suits from people who feel they had their receipts checked on account of race, religion, sexual orientation, national origin, or other legally protected classes that can result in discrimination suits.

It is also a good way to deter some shoplifting, and stores know this from their studies. This is why they both to pay someone to stand at the door to check receipts.