It is primarily responsibility of an individual to apply for leave and get the same approved before proceeding on leave. It is prerogative of the management to sanction or deny leave, which will depend upon the exigencies of work.
In many cases, people go on leave - with an approval - are called back to office on account of emergency / exigencies. Therefore it is management's right to sanction or otherwise. Even in Govt. services and departments (and in defence sectors), employees are called back. That is why, probably you would have seen in the leave letter format, to mention the contact address and phone no underneath, so that the management can contact him/her in case of an emergency. In a renowned Software company, I know my neighbour's friend was pulled to office on his wedding day - immediately after tieing "Mangalsutra". The officers waited for this imporant event to take place and took him to office for that emergency job. He came back and joined his newly wedded wife for lunch later, that was different story.
However, at times it so happens, things are done keeping something in mind. This will be known only when you start probing and analysing the situation.
As far as this employee is concerned, what he did - not submitting approved leave letter - was wrong. You need to communicate to him and ask him to report for duty forthwith.
30th September 2011 From India, Madras