Promises alone don't make a binding contract, but you don't need notaries or witnesses either. A legal contract is an agreement that is enforceable by law. Generally, the law enforces an agreement if one party makes a promise in exchange for valuable consideration to be given by another party.
Contract Requirements
For a contract to be legally enforceable, several conditions must be met. The parties to the contract must be competent adults, the subject of the agreement must be legal, the exchange must be based on valuable consideration and the contract must represent a "meeting of the minds," signifying mutual assent. It is not always necessary that the agreement be in writing.
Various Formalities
Oral contracts are generally enforceable if the terms can be carried out in less than a year. Some contracts, however, must be written to be enforceable. These include agreements involving the ownership of real estate and sales contracts for goods worth $500 or more. No general requirement mandates that a contract be notarized or witnessed in any way to be binding.
References
Writer Bio
Teo Spengler earned a JD from U.C. Berkeley Law School. As an Assistant Attorney General in Juneau, she practiced before the Alaska Supreme Court and the U.S. Supreme Court before opening a plaintiff's personal injury practice in San Francisco. She holds both an MA and an MFA in English/writing and enjoys writing legal blogs and articles. Her work has appeared in numerous online publications including USA Today, Legal Zoom, eHow Business, Livestrong, SF Gate, Go Banking Rates, Arizona Central, Houston Chronicle, Navy Federal Credit Union, Pearson, Quicken.com, TurboTax.com, and numerous attorney websites. Spengler splits her time between the French Basque Country and Northern California.