The group Consumer Action is siding with the salon, saying the laws trample freedom of speech by forbidding businesses from charging credit card fees.
"Merchants should be able to say there is an additional cost and I'm going to be passing it on to you," said Ruth Susswein, Consumer Action's deputy director of national priorities.
New York said the Supreme Court never should have taken the case because it involves business conduct, not speech.
States like New York prohibited swipe fees as a way to encourage credit card use.
Allowing the surcharges would negatively impact sales, the states argued in a brief at the court.
A ruling could narrowly affect New York or could impact credit card fees in all states where they are banned.