ohn is a pharmacist and the manager of a self-serve chemist supermarket, which includes certain medicinal drugs being offered. It is illegal to sell some of these items unless it is under the supervision of a registered pharmacist. The issue that arose was whether the goods on the shelves with prices marked on them constitute an offer that the customer accepted when they took the goods off the shelves. If they were then the contract of sale was formed at this point and was therefore 'unsupervised'.

Advise John and cite an example of relevant case law.