Final answer:
Under the Statute of Frauds, it is typically the defendant's signature that is required on a written contract for it to be enforceable. The U.S. Constitution allows for an act to be tried in both civil and criminal courts because they address different aspects of law.
Step-by-step explanation:
The common-law Statute of Frauds states that certain types of contracts must be in writing to be legally enforceable. These typically include contracts for the sale of real estate, contracts that cannot be performed within a year, promises to answer for the debt of another, and several others. When it comes to whose signature is required, usually it is the party against whom enforcement is sought that must have signed the document. This means that in most cases, it's the defendant's signature that is necessary under the Statute of Frauds.
Regarding being tried in both civil and criminal court, the United States Constitution allows for separate legal proceedings for the same act under certain conditions. This is because criminal charges are considered offenses against the state, whereas civil suits are disputes between private parties over rights and obligations. Double jeopardy does not apply to civil cases; it only prevents a defendant from being tried twice on the same criminal charges.