Final answer:
An exception to the rule that agency contracts require a specific termination date can be found in employment contracts with a probationary period, where the employer can terminate the contract more freely, often at reduced pay for the employee.
Step-by-step explanation:
An exception to the agency rule that contracts must terminate at a specific time occurs in the case of employment contracts with a trial or probationary period. During this period, the employer typically reserves the right to terminate the employment contract for any reason or no reason at all, if the new hire does not meet performance expectations.
This is a precautionary measure against the risk of hiring an employee who may not perform satisfactorily, sometimes referred to as a "lemon" of an employee. It is also common for employees to receive lower pay during this probationary period. This serves both as a cost-saving measure for the employer and as additional motivation for the employee to demonstrate their capabilities.