1. Internal borders may be crossed at any point without any checks on persons being carried out.
2. Where public policy or national security so require, however, a Contracting Party may, after consulting with other Contracting Parties, decide that for a limited period national border checks appropriate to the situation will be carried out at internal borders. If public policy or national security require immediate action, the Contracting Party concerned shall take the necessary measures and shall inform the other Contracting Parties thereof at the earliest opportunity.
3. The abolition of checks on persons at internal borders shall not affect . . . the exercise of police powers by the competent authorities under each Contracting Partys legislation throughout its territory . . . .
Convention, supra note 4, art. 2.