Yes. Companies can create and maintain an attendance policy for all employees. In the event an employee requests UTO and is denied but takes the time off anyway, a company may terminate the employee on at-will grounds. This question is complicated if the UTO request is for reasons included in the Family and Medical Leave Act, which allows for 12 weeks of unpaid leave for specific reasons in a 12-month period. The Department of Labor (https://www.dol.gov/agencies/whd/fact-sheets/28-fmla) states, “It is unlawful for any employer to interfere with, restrain, or deny the exercise of or the attempt to exercise any right provided by the FMLA.”