From the Wall Street Journal
The Justice Department slapped American Express Co. with a civil antitrust suit after the credit-card company refused to join an industrywide agreement to allow merchants to steer customers toward cheaper forms of plastic.
Those who have cash-back AmEx credit cards like the Fidelity's Retirement Rewards
or the Costco Cash Rebate Card
, may find these less rewarding if AmEx is forced to abide by the Justice Department's demands. Merchants may not give you a discount if you decide to use your AmEx card.