Valuable consideration

Consideration is the concept of value offered and accepted by people or organisations entering into contracts. Anything of value promised by one party to the other when making a contract can be treated as "consideration": for example, if A signs a contract to buy a car from B for $5,000, A's consideration is the $5,000, and B's consideration is the car.

Additionally, if A signs a contract with B such that A will paint B's house for $500, A's consideration is the service of painting B's house, and B's consideration is $500 paid to A. Further, if A signs a contract with B such that A will not repaint his own house in any other color than white, and B will pay A $500 per year to keep this deal up, there is also consideration. Although A did not promise to affirmatively do anything, A did promise not to do something that he was allowed to do, and so A did pass consideration. A's consideration to B is the forbearance in painting his own house in a color other than white, and B's consideration to A is $500 per year. Conversely, if A signs a contract to buy a car from B for $0, B's consideration is still the car, but A is giving no consideration, and so there is no valid contract. However, if B still gives the title to the car to A, then B cannot take the car back, since, while it may not be a valid contract, it is a valid gift.

In common law it is a prerequisite that both parties offer consideration before a contract can be thought of as binding. The doctrine of consideration is irrelevant in many jurisdictions, although contemporary commercial litigant relations have held the relationship between a promise and a deed is a reflection of the nature of contractual considerations. If there is no element of consideration found, there is thus no contract formed.

However, even if a court decides there is no contract, there might be a possible recovery under the doctrines of quantum meruit (sometimes referred to as a quasi-contract) or promissory estoppel.

There are a number of common issues as to whether consideration exists in a contract:

Systems based on Roman law (including Germany and Scotland) do not require consideration, and some commentators consider it unnecessary and have suggested that the doctrine of consideration should be abandoned, and estoppel used to replace it as a basis for contracts. However, legislation, rather than judicial development, has been touted as the only way to remove this entrenched common law doctrine. Lord Justice Denning famously stated that "The doctrine of consideration is too firmly fixed to be overthrown by a side-wind".

...
Wikipedia