Final answer:
The missing essential element of a contract in the given scenario is competence.
Step-by-step explanation:
The missing essential element of a contract in the given scenario is competence.
When a person is declared incompetent by the courts, their ability to enter into agreements or contracts is compromised. In order for a contract to be binding, all parties involved must have the legal capacity to understand the terms and consequences of the agreement. If a person is deemed incompetent, they lack the necessary capacity to enter into a legally enforceable contract.
For example, if a person declared incompetent by the courts signs a contract to purchase a car, that agreement would be void because the person lacks the competence to fully understand the terms and implications of the contract.