They're a fairly new innovation to the weekly shop that often cause debate when we see them.

The self-checkout tills are something that always seem to divide shoppers - whether they're in Tesco, Aldi, Morrisons, Asda or Sainsbury's.

While some love using them, there are others shoppers who can't stand the idea of them.

Often they cut down queue sizes and speed things up, and although supermarkets put measures in place to stop people cheating the system, they still often rely on customers being truthful about their purchases.

But the law is the law, and one shopper has been warned that her 'cheeky' tactic at the checkout to save some cash could land her in trouble, as the Manchester Evening News reported.

A woman wrote into 's Sisters In Law, which allows people to put their legal conundrums to sisters and lawyers Alison and Jillian Barrett, about a disagreement she had with a friend.

She said that when her friend uses the self-service checkouts, she regularly puts more expensive fruit and veg - such as an avocado - through the system as a brown onion instead.

The friend believes that it isn't stealing as she's still paying something for it, and claimed the supermarkets work the cost of self-checkout fraud into its prices because "everyone does it".

The lawyers replied to advise: "It doesn’t matter how your friend tries to justify her behaviour, her deceitful conduct in intentionally not paying full price is against the law.

"Your friend’s technique of using the self-service checkout to pass off more expensive items as cheaper ones cheats the system by underpaying. Her fraudulent behaviour is just one of many tricks employed by self-service thieves to avoid payment."

Alison and Jillian, based in Australia, said the 'tricks' are costing supermarkets a fortune every year and are actually pushing up the prices of groceries as a result.

Self-checkouts can weigh items to check you're being truthful, and supermarkets often employ staff and security guards to ensure they are being used correctly - but they also rely on the honesty of their customers.

They warned that "an excuse like getting avocados confused with brown onions is likely not going to cut it" if her friend is eventually caught, and she could being left facing a range of punishments.
