Visa Officially Says Stores Cannot Deny Purchases If You Don't Show ID
According to The Consumerist, here's VISA's official policy on stores requiring ID for a credit card purchase.
Merchants may not refuse to honor a Visa card simply because the cardholder refuses a request for supplementary information. The only exception is when a Visa card is unsigned when presented. However, "See ID" is not considered a valid signature. In these situations, a merchant must obtain authorization, review additional identification, and require the cardholder to sign the card before completing a transaction.
To report any merchant practices that you feel are inappropriate, please notify the disputes area at the financial institution that issued your card account. Your card issuing bank has access to the appropriate Visa rules and regulations as well as to the Notification of Customer Complaint forms which should be used by your bank to document and file merchant complaints.
As an alternative, you may contact the Global Customer Care Services to report merchant practices that you feel are inappropriate. Please contact the Global Customer Care Services at 1-800-VISA-911 (1-800-847-2911). Please advise them that you were referred to file a complaint. The staff will be able to initiate a complaint form over the phone.