Generally,
advertisements are not offers but invitations to treat, so the person advertising is not compelled to sell. In
Partridge v Crittenden [1968] 1 WLR 1204, a defendant who was charged with "offering for sale protected birds"—bramblefinch cocks and hens that he had advertised for sale in a newspaper—was
not offering to sell them. Lord Parker CJ said it did not make business sense for advertisements to be offers, as the person making the advertisement may find himself in a situation where he would be contractually obliged to sell more goods than he actually owned. In certain circumstances called
unilateral contracts, an advertisement can be an offer; as in
Carlill v Carbolic Smoke Ball Company [1893] 1 QB 256, where it was held that the defendants, who advertised that they would pay £100 to anyone who sniffed a smoke ball in the prescribed manner and yet caught
influenza, were contractually obliged to pay £100 to whoever accepted it by performing the required acts. A display of goods for
sale in a shop window or within a shop is an invitation to treat, as in the
Boots case, a leading case concerning supermarkets. The shop owner is thus not obliged to sell the goods, even if signage such as "special offer" accompanies the display. Also, in
Fisher v Bell [1961] 1 QB 394, the display of a
flick knife for sale in a shop did not contravene legislation which prohibited "offering for sale an offensive weapon". If a shop mistakenly displays an item for sale at a very low price it is not obliged to sell it for that amount. For an offer to be capable of becoming binding on acceptance, the offer must be definite, clear, and objectively intended to be capable of acceptance. The
tender process is a debated issue. In the case of
Spencer v Harding, the defendants offered to sell stock by tender, but the court held that there was no promise to sell to the highest bidder, merely an invitation for offers which they could then accept or reject at will. In exceptional circumstances, an invitation for tenders may be an offer, as in
Harvela Investments v Royal Trust of Canada [1986], where the court held that because defendants had made clear an intention to accept the highest tender, then the invitation to tender was an offer accepted by the person making the highest tender. The
Harvela case also made it clear that "referential bids" (e.g. "$2,100,000 or $101,000 in excess of any other offer which you may receive, whichever is the higher", as in the
Harvela case) are void as being
contrary to public policy. ==Auctions==