Tens of thousands of foreigners live illegally in Belgium. The reasons why many are not expelled are manifold, but may include the fact that their country origin is at war or because their children have Belgian citizenship.
Illegal immigrants who qualify for official residence papers are those who meet the conditions laid down in the Law relating to Foreigners of 15.12.1980.
At different periods, the Government has issued decrees setting criteria of “regularising” the stay of illegal migrants. For example at the end of 1999, the government drafted a special law allowing illegal immigrants to acquire the right of abode in Belgium under well-defined terms and conditions. It was applicable for just three weeks. General conditions included proof of identity, proof of residency in Belgium and evidence that the person is known to a public authority. Specific conditions referred to the fact that the applicant must fit into one of the following four categories: that they have been an asylum-seeker for at least four years (three years for families with children of school age); that they are unable to return to their country of origin for reasons beyond their control; that they are seriously ill; or that they can give another evidence of humanitarian reasons for staying in Belgium.
Although the Law of 1999 is not applicable any longer, those criteria can still be used under Article 9 bis of the law of 15.12.1980. In this regard, the Administration (i.e. Dienst Vreemdelingenzaken / Office des Etrangers) has a very large margin of appreciation in deciding whether the quoted elements justify an authorisation to legal stay or not.