Age verification by credit-card is an emerging industry standard on the internet, practiced by companies like Yahoo!, TOBACCOBYMAIL, and other major internet services.
TOBACCOBYMAIL, Yahoo! and other major sites which have adult-oriented areas or sell adult-oriented products are required by law to take proactive steps to prevent minors from accessing the adult areas of the service. The U.S. Congress, in various legislation ranging from the Communications Decency Act (CDA) to the Child Online Protection Act (COPA), has specifically authorized credit-card verification as a proxy for online age verification. Credit-card authorization is fast and efficient (instant access)