In common law jurisdictions, an implied warranty is a contract law term for certain assurances that are presumed to be made in the sale of products or real property, due to the circumstances of the sale. These assurances are characterized as warranties regardless of whether the seller has expressly promised them orally or in writing. They include an implied warranty of fitness for a particular purpose, an implied warranty of merchantability for products, implied warranty of workmanlike quality for services, and an implied warranty of habitability for a home.

The warranty of merchantability is implied, unless expressly disclaimed by name, or the sale is identified with the phrase "as is" or "with all faults". To be "merchantable", the goods must reasonably conform to an ordinary buyer's expectations, i.e., they are what they say they are. For example, a fruit that looks and smells good but has hidden defects would violate the implied warranty of merchantability if its quality does not meet the standards for such fruit "as passes ordinarily in the trade". In Massachusetts consumer protection law, it is illegal to disclaim this warranty on household goods sold to consumers.

The warranty of fitness for a particular purpose is implied when a buyer relies upon the seller to select the goods to fit a specific request. For example, this warranty is violated when a buyer asks a mechanic to provide snow tires and receives tires that are unsafe to use in snow. This implied warranty can also be expressly disclaimed by name, thereby shifting the risk of unfitness back to the buyer.

Another implied warranty is the warranty of title, which implies that the seller of goods has the right to sell them (e.g., they are not stolen, or patent infringements, or already sold to someone else). Theoretically, this saves a buyer from having to "pay twice" for a product, if it is confiscated by the rightful owner, but only if the seller can be found and makes restitution.

Fitness for a particular purpose

An implied warranty of fitness for a particular purpose occurs if a seller knows or has reason to know of a particular purpose for which some item is being purchased by the buyer. The seller then guarantees that the item is fit for that particular purpose.

International sales law

In international sales law, the obligation is found in Article 35(2)(b) of the United Nations Convention on Contracts for the International Sale of Goods.

Australia

In Australia, the obligation is in section 55 of Schedule 2 ("The Australian Consumer Law") of the Competition and Consumer Act 2010 (Cth) for consumers. The Sale of Goods Acts in each state also implies the warranty and is not limited to consumer contracts.

United States

In the United States, the requirement for an implied warranty of fitness for a particular purpose (sometimes shortened to warranty of fitness) is found in .

United States

In the United States, the requirement for an implied warranty of merchantability is found in . The doctrine is intended as a protection for tenants in a less advantageous bargaining position than the landlord. The warranty of habitability can be breached if there is no heat, hot water, or other essential services. Safety issues like no smoke alarm or other fire code issues can also be considered to make a dwelling uninhabitable. In some cases, courts have ruled that the warranty also covers cracked walls, peeling paint, and leaks.

Contractual language can also limit the remedies available for breach of an implied warranty such as by capping recoverable damages or limiting the legal remedy to a replacement of a defective item. However, such a term can be found to be unconscionable. For example, if a defective product causes a personal injury, a contractual provision limiting recovery in such a case will be deemed prima facie unconscionable.

  • The GNU Project's General Public License, a prominent free software license, includes the disclaimer: "Except when otherwise stated in writing the copyright holders and/or other parties provide the program 'as is' without warranty of any kind, expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose."