My husband was terminated because he "missed" too much work. However. He has doctors notes to be excused. Would there be a case?

Employers are not required to allow an employee time off work, even with a doctor's note, unless the time off is covered by FMLA. If the time off is covered by FMLA, then the employer must allow the employee time off.  In rare circumstances, an employer is required to allow an employee time off as a reasonable accommodation under the Americans With Disabilities Act.