Hypothetically, if a self-service checkout at my local Tesco were to be malfunctioning and selling items for half-price, and if someone were to exploit this to buy cheap goods, would this be considered theft under UK law?
In the Theft Act 1968:
A person is guilty of theft if he dishonestly appropriates property belonging to another with the intention of permanently depriving the other of it.
Does the purchase of goods at half the marked price constitute dishonest appropriation? An argument that it doesn't might be that the self-service checkout has authorized the purchase and the requested amount has been paid, thus there is no dishonesty involved.
However, the checkout is obviously not intended to operate this way, and the price shown by the checkout obviously doesn't match that of the displayed price in the shop. Does this mean that by knowingly still buying goods like this, the purchaser is being dishonest?