What can make a contract invalid?

One factor that can render a contract invalid is if one party lacks the necessary competence to enter into a contractual agreement. Competence typically refers to the legal ability to enter into a contract, which can include aspects such as mental capacity and soundness of mind. If a party is deemed incompetent—due to reasons such as mental illness, being intoxicated at the time of signing, or other factors that impair judgment—their consent to the contract is not considered valid. Therefore, the contract itself loses enforceability since the agreement lacks the foundational element of mutual consent from parties capable of understanding the terms and implications involved.

While being underage can also affect the validity of a contract, this is generally a specific situation governed by the laws of minors, which could lead to the contract being voidable rather than entirely invalid. The presence of both parties signing the contract and its verbal nature often do not inherently invalidate it but can introduce other legal considerations regarding enforceability.