The Constitution does mention 'contracts,' and more than once. Problem is, I don't see joining an HOA as a contract any more than a person being born in the U.S. having a citizenship contract. Naturalized citizens actually do sign a contract that states they have chosen to be a citizen; they are 'sworn in' and agree to uphold the Constitution and American laws. Native born citizens don't sign anything, nor are they sworn in. It's a preclusion, just as HOA membership is when you buy property in one. No contract involved.