We've probably all done it – gone to the pub for a leisurely Sunday lunch or had a few drinks after work and happily handed over our credit card to run a "tab". But while it saves dipping into your pocket every time you go to the bar, if your card is lost or used fraudulently, you could in theory be held responsible.
CNP (cardholder not present) fraud has soared over the past few years. The most recent figures, for the first half of last year, show scams of this sort up 44 per cent compared with the same period in 2006.
Sandra Quinn from the Association for Payment Clearing Services says: "CNP fraud is the biggest single type of fraud we have and it's no great secret that we're expecting the figures to be even higher this year."
These statistics can't be attributed solely to fraudulent activity taking place while credit cards are out of sight behind a bar. However, handing over your card to run up a tab is "definitely a security risk", says Tim Pie at HSBC. "We'd recommend our customers ask why it's necessary for the pub or restaurant to take the actual card, as letting it out of your sight can in some circumstances lead to it being skimmed."
The widespread practice of skimming, the illegal copying of card details and pin numbers electronically, is made easier for criminals when the card is out of the owner's possession for a long time.
Ms Quinn points to the terms of the Banking Code, which state that customers have a responsibility to take "reasonable care" of a card, but says there are no ground rules and that "it would depend on your relationship with your card company as to how they would handle the situation".
Barclaycard has more than nine million credit cards in circulation in the UK, and it too places ultimate responsibility with the customer.
"Cardholders should never let their card out of their sight, and this includes handing them over to run tabs in bars and restaurants," says Barclaycard's Sarah Conyers.
Other banks and card providers, including the Halifax, Sainsbury's and Egg, strongly advise customers against this practice.
Chris Holloway is a founder of CardsSafe, a company that has produced a lockable unit for customers' cards, for use in pubs and restaurants. He says: "When you think that the average number of cards behind the bar could run to 20 or 30 on a busy weekend night, with some pubs sticking cards in glass jars behind the counter, on shelves and even on clipboards, you can see how easily card fraud can occur."
But whatever security measures are in place, if there is a corrupt member of staff at your local, you could become a victim of fraud. Don't think, either, that you can necessarily rely on insurance products such as a cardholder protection policy to fund any losses that arise. As Malcolm Tarling from the Association of British Insurers says: "The general principle under any insurance is that you've got to take reasonable care." He admits, though, that the waters are muddied, since there is no clear definition of "reasonable care".
Ultimately, the advice from banks and credit card companies is to hang on to your plastic at all times. Bear in mind, too, that the new methods being employed by pubs and restaurants to improve credit card security aren't just about giving customers peace of mind; they're also designed to put more money in the till. We spend an average of 30 to 50 per cent more by setting up a tab than if we had kept hold of our cards and paid the bill in cash.