As Switzerland voted on the integration of the Schengen acquis into Swiss law, many parties pretended that security would be reduced, with more criminals being able to enter the country uncontrolled at the borders. This of course was non-sens, since only 90% of the entrants used to be checked in the non-Schengen system. Now, an interesting, challenging exercise will take place: how to prove that Schengen did increase security? It will be impossible to do. In the semi-evaluation we have already be presented, police froces and ministries shake their hands proudly on the high number of inquiries into the database (SIS) and on the high ratio of hits (inquiry with a match in the database). This is pure "inputs" analysis. The true question is: what do these inquiries and hits concern? If it is, as we assume, mainly administrative issues like immigration regulation, then is has no link with security at all. Pretending so would de facto mingle immigration and insecurty, an old aim pursued by Swiss and European (far-)right parties. But as long as Schengen only allows to catch individuals with unvalid immigration papers, it can not be said to improve security. This would be simply untrue. Secondly, how will it be possbile to show that in the previous system, i.e. with border controls, these cases would not have been identified? Some extrapolations will probalby be made, relevance of which will have to be questioned. In brief, Schengen probably changed nothing to the security situation of Switzerland: no cost (increasing insecurity) and no benefit (better security). Schengen is an internal market policy, more precisely a labour market one, and any attempt to make it a security policy is for the time being more rethoric than factual.