Your credit card comes with Terms and Conditions.  You've never read them.  But they include, somewhere around page 18, a warning that if you make any payment late, the card issuer has the right, if it wants, to increase the interest rate that applies to your Outstanding Balance.  And it may do so retroactively.  Without

California law favors class actions.  So much so that Golden State courts have struck down class-action bans that show up in consumer contracts whether they apply to lawsuits, Discover Bank v. Superior Court of Los Angeles, 113 P.2d 1100 (Cal. 2005), or arbitration cases, America Online v. Superior Court, 108 Cal. Rptr. 2d 699