Fixing the problem can be accomplished in three steps:
1. Review your organization’s written policy with the help of legal counsel in order to ensure that you’ll be able to retain the most discretion in managing this thorny issue.

2. Review your organization’s past practices (for example, all of the disciplinary actions and terminations related to unauthorized absence in the past two years) across departments, divisions, and locations. Account for inconsistencies in prior decisions. Remember that you retain the discretion to change a policy or practice by notifying employees in advance and in writing: You’re not obliged to perpetuate a problem once
you discover that changing the rule or practice could make things better. Simply follow a rule of reason: If employees are given advance notice of the organization’s changed expectations, they should be held accountable for meeting the new standard on a go-forward basis.

3. Document substandard performance consistently.

A sample documentation letter appears in Appendix Q. List the dates and days of the week of the actual incidents. In addition, document the negative organizational impact that resulted from the individual’s unauthorized absenteeism.

Finally, if your policy does not spell out the specific number of incidents that could lead to termination, include general consequential language. On the other hand, if your company policy spells out the number of incidents of unscheduled absenteeism that will result in dismissal, include that specific information instead.

Taken From : The Hiring and Firing Quention and Answer Book