This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
A contract made between competent parties, and apparently having all the legal requisties of a good contract, may still under certain circumstances be set aside by the court. If in the formation of a contract there has been mistake, misrepresentation, fraud, duress, or undue influence, the injured party may, by proper legal proceedings, avoid the agreement. Such mistake as may be the basis of relief must not be mere careless mistake; it is in many cases of such a nature as almost to involve misrepresentation or fraud. Duress occurs where the consent of one party is obtained by violence. Undue influence implies that the will of one person is absolutely overcome by the will of another, so that the consent of the first is not really an independent act. Perhaps the most important of the above-named grounds of avoidance is fraud. In case a contract has been entered into upon a material and wilfully false representation by the other party, it may be avoided. Occasion for this may arise, for instance, upon deception in the purchase of materials.