The joint Belgian - French patrols are supposed to have a discouraging effect on French punters. Here in Belgium paying for the services of a prostitute is, of course, entirely legal.
Police officer Roger De Beule: "We've noticed that disturbing things happen in the margin of visits to a Belgian prostitute. Our plan is to clamp down on that kind of disturbing behaviour."
"Making noise at night is against the law here as is being drunk in a public place and we will move against such offences."
Similar joint patrols already exist in Ghent.