A Maryland court ruled that a credit card company could not force customers into arbitration because they never actually agreed to it. The bank tried to add an arbitration clause to an existing cardholder agreement, but Maryland law required proper amendment procedures that weren't followed. The court held that the Federal Arbitration Act doesn't override state law on how contracts are changed, and you can't be forced to arbitrate if you didn't sign up for it.
Contract amendments must follow the state law requirements where the contract was made—you can't just slip new terms into an existing agreement without proper notice and acceptance.
If a contractor or supplier tries to add an arbitration clause to an existing agreement, verify it was done correctly under your state's law before accepting it as binding.