Final answer:
The legality of the decision will depend on the specific circumstances and applicable laws, regardless of Mia's status as an employee at will.
Step-by-step explanation:
The term 'employee at will' refers to the employment relationship in which either party, the employer or the employee, can terminate the relationship at any time and for any reason, as long as it is not a discriminatory or illegal reason. In the context of the question, the legality of the decision would depend on the specific circumstances and applicable laws. While being an employee at will does provide the employer with certain flexibility, it does not allow them to make decisions that are illegal or discriminatory.