Legal Definitions - Catoniana regula

The Catonian Rule (Catoniana regula) is a legal principle stating that if a contract or legal act is invalid from the moment it is created, it cannot become valid later, even if the obstacle that made it invalid is subsequently removed. Essentially, if an agreement is fundamentally flawed or impossible at its inception, it remains void and cannot be "cured" by later events.

• Example 1: Contract with a Minor

  Imagine a 16-year-old signs a contract to purchase a luxury car. In many legal systems, contracts entered into by minors are considered voidable or void from the outset to protect the minor's interests.

  Under the Catonian Rule, even if the teenager turns 18 the very next day, the original contract signed when they were a minor remains invalid from its inception. The fact that they are now an adult does not automatically validate the original agreement. To make the purchase legally binding, the parties would typically need to enter into a new contract or the now-adult would need to ratify the original contract with full legal capacity.

• Example 2: Agreement for an Illegal Purpose

  Consider two individuals who enter into a contract where one agrees to pay the other to transport a large quantity of goods that are explicitly prohibited by law at the time of the agreement.

  This contract is void from its very beginning because its purpose is illegal. According to the Catonian Rule, even if the law changes a year later, making the previously prohibited goods legal to transport, the original contract remains invalid. The initial illegality at the moment of formation prevents it from ever becoming a valid, enforceable agreement.

• Example 3: Contract for a Non-Existent Item

  Suppose a collector signs a contract to buy a specific, unique antique sculpture from a dealer, unaware that the sculpture had been accidentally destroyed in a fire just hours before the contract was signed.

  Since the subject matter of the contract (the specific sculpture) did not exist at the time the agreement was made, the contract is void from its inception due to impossibility. The Catonian Rule dictates that even if the dealer later finds an identical sculpture, the original contract does not become valid. A new agreement would be required for the collector to purchase the newly found item.