Shoppers have been sent a warning over a little-known law they could be breaking when they're out at the supermarket.

Most people would never dream of walking into a shop and take a product without paying for it first.

But, this is exactly what some supermarket shoppers do as they just can't wait until they get home to eat one of their purchases.

READ MORE:Every driver warned over law you could be breaking when filling up your car

It could be a bar of chocolate or the sandwich from a meal deal but it's not uncommon to see a shopper pop an empty packet onto the conveyor belt with the rest of shopping.

While this habit may seem completely innocent, criminal law specialists Adkirk Law in Southport has warned you could be breaking the law.

Rachel Adamson says very few people realise that the product is only yours once the sale is complete.

She said: "While you might have the honest intention to pay for a chocolate bar that you’ve eaten while shopping in a supermarket, it is still technically illegal under section 6 of the Theft Act 1968.

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“Buying a product at the till is what transfers the ownership from the product belonging to the shopkeeper, to it belonging to you. And only when that sale is complete do you have the legal right to consume or use it. If you eat the chocolate before you legally own it, you are permanently depriving the owner of his right to the product – he can no longer refuse you the sale or take the item off the shelves.

“In another example, it would be like redecorating a house before you’ve exchanged contracts or spray painting a car while it’s still in the showroom. Even with the honest intention of buying the product, you shouldn’t alter or use something that isn’t yours.”

Ms Adamson said: "Worryingly, new legislation is also catching people out such as the illegal use of wi-fi or the illegal downloading of music or certain documents, which now seem entirely natural to do without asking.

“It is also illegal to send unsolicited mail to another person without their consent under the data protection laws and people have been prosecuted for it.”

The laws on data protection say you can only send emails to individual subscribers if they have 'previously notified the sender' of their specific consent to receiving such emails.

Rachel urges caution. She added: “Be careful. We should all consider the possible consequences before we engage into some of these things - you could be breaking the law on something important and end up in court. Take advice first if you are in any doubt.”

Adkirk Law is a leading UK Law firm offering a niche practice with expertise in regulatory law including serious fraud, regulation and police misconduct.

Regulatory breaches can result in enforcement action being taken against businesses or individuals.

Any breach of regulations or obligations can result in loss of registration with regulators, criminal prosecution, prohibition notices and other serious sanctions.