An exception arises when advertising makes a unilateral promise, such as offering a reward, as decided in the famous case of Carlill v Carbolic Smoke Ball Co, in 19th century England. The company, a pharmaceutical manufacturer, proposed a smokeball that, if it sniffed „three times a day for two weeks,“ would prevent users from catching the „flu.“ If the smokeball does not prevent „the flu, the company promised that it would pay $100 to the user, adding that they deposited „$1000 in the Alliance bank to show our sincerity in the file.“ When Ms. Carlill complained about the money, the company argued that the complaint should not be considered a serious and legally binding offer; instead, it was a „simple mess“; However, the Court of Appeal found that Carbolic had made a serious offer to a reasonable man and found that the reward was a contractual undertaking. Under Australian law, a contract can be cancelled due to an unscrupulous trade.   First, the applicant must show that he was subject to a particular disability because he could not do so in their best interest. Second, the applicant must show that the defendant used this particular obstruction.   After an offence, the innocent party has a duty to mitigate the loss through appropriate action. Non-reduction means that damage can be reduced or even denied.  Professor Michael Furmston  argued, however, that it is „wrong to express (the mitigation rule) by stating that the plaintiff is obliged to mitigate his loss“, referring to Sotiros Shipping Inc.
against Sameiet, The Solholt.  When a party indicates that the contract is not concluded, an anticipated infringement occurs. A contractual clause is „a provision that is part of a contract.“  Any clause gives rise to a contractual obligation, the violation of which may give rise to litigation. Not all conditions are explicitly specified and certain conditions have less legal weight, as they are marginal in the treaty`s objectives.  In the United States, an unusual type of non-opposable contract is a personal employment contract to work as a spy or secret agent.