This article De Morgen raised some concerns for me. The link is in Dutch; the following are the sections relevant for my question, in English courtesy of Google translate:
In response, Minister of the Interior Annelies Verlinden (CD&V) launched, among other things, a new database in which everyone who has ever been banned from a recreational area or seaside resort is included. [...] The use of the database is combined in Blankenberge with systematic identity checks.
The first part of the article describes what is effectively just increased vigilance by the police - keeping an extra eye on known or suspected troublemakers. But then:
[...] Bart Tommelein, Open Vld mayor of Ostend, goes one step further. Anyone who appears in that database and is recognized by the sea, has no place in the queen of seaside resorts. “I have a tit-for-tat policy,” says Tommelein emphatically. “Those amok makers are known, and not in a positive sense. You don't just get a restraining order. Anyone on that list already has a few things on their record. We don't need them here." In Ostend, the young people involved will therefore be administratively detained and sent home again.
As I understand it, the restraining orders (plaatsverboden) are an existing, uncontroversial judicial instrument, with a well-defined scope (e.g. you got caught doing vandalism in Blankenberge, so as part of the sentence you might be barred from Blankenberge), pronounced as part of run-of-the-mill criminal procedures and presumably with some possibility of appeal.
But mayor Bart Tommelein seems to be claiming a right to bar anyone from Ostend if he feels they don't belong there. In this case he happens to be making that decision based on whether the individual has active restraining orders in other seaside municipalities, but legally I don't see how that's distinct from Tommelein barring arbitrary people.
Can Belgian mayors do this? If so, from where do they derive this authority? Is the decision a special power reserved exclusively for the mayor, or can the police also do this on their own initiative? And finally, if I feel I am being unfairly ejected from Ostend, what legal recourse do I have?