Agreement by persons of unsound mind refers to a legal contract made by a person who is not in their normal mental state. Such a contract may be made by a person who is suffering from a mental illness, a person who is intoxicated, or a person who is under the influence of drugs.

In general, agreements made by persons of unsound mind are not considered legal. This is because such individuals do not have the capacity to understand the terms of the agreement. However, there are some exceptions to this rule, which we will explore below.

One of the main exceptions to the rule that agreements made by persons of unsound mind are not legally binding is when the person entered into the contract while they were of sound mind. In such a case, the agreement will be considered valid, even if the person later becomes mentally ill or intoxicated.

Another exception is when the other party to the contract was aware of the person`s unsound state of mind but still went ahead with the agreement. In this case, the other party will not be able to use the unsoundness of mind as a defense in case a legal dispute arises.

Additionally, if the person who was of unsound mind at the time of making the contract has since recovered and is now of sound mind, the agreement will be considered valid. This is because the person is now in a position to understand the terms of the contract.

It is important to note that agreements made by persons of unsound mind are still subject to other legal requirements, such as the need for consideration, mutual consent, and legality of the subject matter.

In conclusion, agreements made by persons of unsound mind are generally not considered legally binding unless certain exceptions apply. It is important to seek legal advice when entering into contracts with individuals who may not be of sound mind, as the legal implications can be complex.