The California Supreme Court surprised a lot of us when it just recently found that retailers who ask customers for their zip codes are violating California’s Song-Beverly Credit Card Act of 1971, which prohibits a merchant from requiring a consumer to provide “personal identification information” as a condition of accepting payment by credit card.  The Supreme Court found that zip codes can constitute such information because they can be reverse-matched to a person’s name and address using a variety of readily available sources.  Note that there are significant penalties that may be applicable under the Act, and merchants should be advised to stop similar zipcode-collecting practices.  There are, of course, other kinds of information that could similarly be reverse-matched to names and addresses — such as email addresses.  This suggests merchants need to reevaluate and consider further refining, if not curtailing, of their point-of-sale data collection practices.