Shoppers have discovered a devious new way to steal from stores

Self-service checkout lanes are everywhere.

Walmart, Target, Kroger, Whole Foods, and CVS are among the many retailers that offer the self-service technology, which allows customers to scan and bag their own purchases.

But there's an alarming downside to the self-checkout lanes: they encourage even the most honest shoppers to become petty thieves, according to a new study cited by the New York Times.

"Retailers could find themselves accused of making theft so easy that some customers who would normally - and happily - pay are tempted to commit crime, especially when they feel 'justified' in doing it," the researchers said. The study was conducted by Professor Adrian Beck and Matt Hopkins of the University of Leicester in England.

The study found that self-checkout technology typically generates "significantly high" loss rates of nearly 4%.

Losses can come from a number of issues. Customers either deliberately or accidentally fail to scan some items by leaving them in their cart. They can also make mistakes in the scanning process - for example, identifying higher-priced organic produce as conventionally grown, which costs less.

For example, one retailer described an incident where a shopper didn't scan all his items:

"This guy scans three items, pays for those three items, punches in his card details, which is great for us because we can track him… but there's five items that haven't been scanned, and soon as he's got his receipt, he bags those up. That to me would be strong enough to put in front of the police and say this is absolutely premeditated, he's decided he's going to steal them, you can see by his behavior he's made no attempt to pay for them."

But retailers are very wary of prosecuting shoppers, because it's potentially a "legal and customer relations minefield," researchers said.

"Giving customers the freedom to self-scan gives them the opportunity to blame faulty technology, problems with the product barcodes or claim that they are not technically proficient as reasons for non-scanning," the researchers wrote. "Proving intent is difficult where customer nonscanning is identified and deciding whether prosecutions can be made or not is potentially a legal and customer relations minefield."

Beyond the legal issues, there are reputational implications.

"Across some jurisdictions retailers have been concerned about potential reputational damage that might be caused by prosecuting customers for not scanning a small number of items," the researchers said.