During the 20th century there was a gradual shift in emphasis in the law governing the formation, interpretation and remedies for breach of contracts. It is not easy to summarize the character of this shift nor possible to predict whether the direction of movement will continue during the 21st century. One aspect of this shift away from classical contract law can be seen in the development of the doctrine of unconscionability, the notion that courts should refrain from enforcing contracts or provisions of contracts that are unconscionable.

Through the 18th and 19th centuries, courts had taken the position that if the technical requirements of consideration and mutual assent had been met (and there had been a writing where required by the Statute of Frauds), the contract should be enforced as made, whether the courts thought the contract was "fair" or "unfair." An exception to this view can be found in courts of equity during these centuries. If the plaintiff (petitioner) asked for an injunction to enforce a contract and the court believed the contract to be unfair, the court would refuse to issue the injunction. This was seen as a specific application of the concept that courts of equity existed to "do equity," to achieve a just result, or, at least, to refrain from using their power to achieve an unjust result. The law courts, to the contrary, were seen as instruments of the law, as appliers of legal rules. The intention was, of course, that those rules would achieve justice in general, but not necessarily in the individual case. It was wiser, therefore, to allow parties to make their own contractual terms than to assert the power on the part of the court to make those terms, even though, in an individual case, the terms might be unfair to one of the parties. These two opposing views of the role of courts continue to this day. What has changed is that, at least in extreme cases, the courts of law (now merged with the courts of equity) will refrain from using the power of the courts to allow one party to achieve unconscionable ends.