And the fixed controls at internal borders have a part to play in stopping this trafficking, as the recent seizure of 106 kilograms of heroin at Calais, with the help of a French customs scanner - an instrument which is, by definition, fixed - has just made clear.
For at standse den, kan de faste kontroller ved de indre grænser dog spille en rolle, som det lige er blevet bevist ved opfangelsen af 106 kg heroin i Calais takket være en scanner, der pr. definition er fast, hos det franske toldvæsen.