The statute of limitations for credit card debts starts running after the last transaction was made on the card, e.g. a purchase using the credit card or a payment made on the card, and runs up to 4 years as per the California Code of Civil Procedure 337.

If you are being sued by a collection agency after the statute of limitations expires, then you can raise a defense of time-barred debt. Contact and consult with a lawyer who is knowledgeable in cases involving credit card debts.