John Cardegna (plaintiff) entered into several deferred-payment transactions with Buckeye Check Cashing (Buckeye) (defendant). Under these transactions, Buckeye gave Cardegna cash in exchange for a personal check plus a financing fee. For each transaction, the parties signed an agreement containing an arbitration clause. Cardegna sued Buckeye, alleging that the agreements violated Florida state consumer-protection laws, making the agreements void ab initio. Buckeye filed a motion to compel arbitration based on the arbitration provision in the agreements. The trial court denied the motion, ruling that courts are the proper forum for determining whether a contract as a whole is invalid, even if the contract contains an arbitration provision. The court of appeal reversed, finding that because Cardegna did not challenge the arbitration clause itself, the clause is valid, meaning that the issue of the contract’s legality should go to an arbitrator. The Florida Supreme Court reversed the court of appeal. The United States Supreme Court granted certiorari.