Many of the medical conditions and disabilities affect an employee's attendance and specifically - an employee's ability to report to work regularly at a scheduled time. Some of the more common such conditions that I see are sleep apnea and extreme cases of depression where an employee is unable to even get out of bed in the morning due to severe panick attacks and other mental or psychological symptoms. When an employee is terminated for absences associated with these kinds of attendance issues, a careful analysis of the facts of his/her employment termination is need to determine whether there is a legitimate wrongful termination claim that can be brought. This often turns on the critical question of whether allowing an employee to have unexpected absences or be late without prior notice to the employer could be a reasonable accommodation to that employee's disabiltiy. 
Some of the questions an employee and the attorney should be asking are: 
* Was an employer on notice of the employee's disability/medical condition? 
* Did the employee request any kinds of accommodations, such as termporary medical leave or modified schedule that would help deal with the attendance issues? What was the employer's response? If the employer refused to provide modified schedule, do the employer's reasons for that refusal seem to be legiimate and supported by business necessity.
* Given the employee's title and job duties, how critical is it for him/her to be punctual and not have any attendance issues? 
* How many employees were perfoming the same job at the same time, and how burdensome it would be for an employer to have those other employees take over the disabled worker's tasks while he is out?
* Was the employee able to give advance notice to the employer about not being able to make it to work?  

The above questions are governed by common sense and seek to flush out whether it was feasable for the employer to accommodate employee's attendance issues, and whether it was reasonable to expect from the employer to provide those accommodations, given the nature and the size of the business as well as the specific duties of the employee.