In general I think payment processor are not required to associate with anybody. The government (in the US at least) is limited in their ability to prevent you from buying guns and making porn (a form of speech), but they can’t make people do the transactions with you; the right to have somebody process payments for you is not constitutionally protected.
But I’d be at least curious (as a non-lawyer) if there could be issues around discriminating against pregnant women in the US, since abortion is a service that is only used by them.
The payment processors interpret the networks’ rules, you do understand that right? If they’re banning something, it’s because the networks either outright are banning it too or have put enough restrictions and constraints in place that the liability for the transaction doesn’t make sense.
The payment processors are doing what the networks tell them to do.
It’s not like the processors are actively looking for ways to turn down money; they want as many transactions going through them so they can earn their share of it.
There were several efforts to restrict the people’s right ability to marshal resistance to tyranny and Visa/MC was very much involved with that even though they were not the only ones.
