When can an employee take a vacation?

Where a lot of confusion occurs, is if an employer has the power to instruct their employees when they can take vacation. Simply, employers have the final say as to when an employee can go on their vacation.
An employer has the right to manage its business as it deems best, and that includes setting the hours of operation and assigning vacation time for employees.
Of course an employee can ask for certain times in the year, and more often than not, an employer will accommodate the employee, but in the end they do not have to. The final decision lies with the employer. Unless an employee has a contract stating otherwise or there is a workplace policy covering vacation time, the employer has the ultimate call about when an employee may take their vacation. However, once an employer tells an employee he or she can take time off the employer could face consequences for revoking the decision later on without very good reason.