excerpt:
“By now, tip overage preauthorizations should be a thing of the past. In 2004, Visa U.S.A. established a 0% tip-authorization policy for restaurants. Likewise, MasterCard International stipulates that restaurateurs must not add a tip without the cardholder’s prior knowledge and agreement.Yet the issue still arises, with misinformation abounding, particularly in the case of a newspaper blog where some discussion participants last August thought restaurants were actually billing extra for tips that were never left. Their ire illustrated the downside of the practice, particularly for debit card users who keep their account balances low. A one-week hold on funds never spent can be frustrating…”
source: “When restaurants exceed the tipping point” (The Green Sheet, Jun.28,2006)