Final answer:
The Statute of Frauds ceases to be applicable as a defense once a contract has been fully performed, because its purpose is to prevent fraud in non-written agreements and full performance evidences a completed contract.
Step-by-step explanation:
The Statute of Frauds refers to legal requirements that certain types of contracts be written and signed. However, once a contract has been fully performed by all parties involved, the ability to invoke the Statute of Frauds as a defense to enforcement of the contract ends. Traditionally, the Statute of Frauds becomes irrelevant upon full performance because the statute's main purpose is to prevent fraud in the enforcement of certain agreements that have not been put in writing. Thus, if a contract has been completed and the obligations have been fully met by both sides, the contract is considered executed and the Statute of Frauds can no longer be used to challenge the contract's validity.