I get a creepy feel that your organization needs some competent people within its senior management and the HR department too. Also as a premonition, you probably may be hearing soon from one of the Employee Associations or Unions to explain your policies and procedures, specifically your disciplinary procedures.
PS: Labor commissioners are tightening their rules in dealing with employee grievances, so you may want to be a little careful in being too stringent with discipline
Discipline is a major factor in any of the establishment or factories and absenteeism without any intimation or authorization is also a major misconduct but at the same time, the employee concerned should also be heard before proceeding further. Even one or half day casual leave or sick leave can be availed without prior approval depending upon the circumstances.
Such absentee should be issued a show cause notice asking his written explanation and is let off with a warning. If a person repeats such misconducts on more than three occasions in a calender year, then it is treated as habitual.
Its not a big issue, we needs to concentrate on big issues of company rather than small issues.
You can give verbal warning in presents of his supervisor and inform not to repeat the same.
If you feels that he will repeat the same again and again than follow your policy guidelines.