Legal Matters: Collecting Customer ZIP Codes? 
Beware the Legal Risks

Impact of the Court's Decision
As a result of this decision, retailers are now prohibited from collecting ZIP codes from California credit card customers unless one of a limited number of exceptions applies. In fact, the restriction goes beyond ZIP codes to any "information concerning the cardholder" that doesn't appear on the credit card itself. Under the reasoning adopted, collection of a California customer's email address, state of residence or even marketing preferences could constitute violation of the statute.