The incident occurred when Wim De Troy, who hit the headlines last year as the Brussels magistrate in charge of the investigation into an alleged cover-up of sexual abuse by clergy, drove to Sint-Gillis to sign the detention order of a suspected drug dealer. He arrived in his private car, and the guard at the gate would not let him drive his car into the prison. De Troy called for the chief prison officer, who upheld the other guard's decision. The two officers were then supported by the prison director on duty that evening.

De Troy's response was to call the special unit of police that covers Zaventem airport, where the case against the alleged drug dealer is being handled, and have the three arrested for obstruction of an official investigation. They were detained and questioned at the airport, while De Troy signed the detention order.

"At first glance it appears the prison personnel behaved correctly," De Clerck said at the weekend. "If what is emerging now turns out to be true, I find it an extremely strange reaction from a magistrate. It is out of all proportion....We make a lot of effort to help the prison system work properly. The historically low prison escape figures for 2010 show that we're on the right track. A magistrate cannot be allowed to ignore the rules."