Article 36 TFEU contains a number of listed grounds upon which Member States may attempt to rely upon, to justify national measures that derogate from giving effect to the free movement of goods. One of these listed grounds is public security, and is specifically contained in the respective internal market freedoms provisions in the EU Treaties. Prior to Campus Oil, the ‘public security’ term, at least in regards to the free movement of goods, had not been interpreted or applied by the Court. Thus, with AG Slynn assigned to the case, it afforded him the opportunity to give the first judicial pronouncement of the Court on how public security was to be understood in this regard to this foremost freedom. Given this first mover advantage, AG Slynn had the opportunity to shape the interpretation of the concept within internal market law, beyond merely the case at hand, but more broadly on the notion of security and EU law.

The question in Campus Oil was, essentially, how far the public security (sécurité publique) exception extended for Member States to derogate from the premise of free movement. There were and are two opposing views. On the one end of the spectrum is the view that public security is a delicate matter for the nation state to protect and defend its interests. On the other end of that spectrum is a narrower structural view that sees any measure of a Member State, in the name of public security, as hampering the effectiveness of free movement. Where the case law on this matter comes down is ultimately a matter of several considerations, commencing in Campus Oil as regards trade in goods. The Campus Oil case is essentially known for how Member States may successfully invoke the public security exception, but simultaneously, how that its invocation must be sufficiently justified, in light of given circumstances.