“28. The existence of a previous criminal conviction can, therefore, only be taken into account in so far as the circumstances which gave rise to that conviction are evidence of personal conduct constituting a present threat to the requirements of public policy. 29. Although, in general, a finding that such a threat exists implies the existence in the individual concerned of a propensity to act in the same way in the future, it is possible that past conduct alone may constitute such a threat to the requirements of public policy. 30. It is for the authorities and, where appropriate, for the national courts, to consider that question in each individual case in the light of the particular legal position of persons subject to Community law and of the fundamental nature of the principle of the free movement of persons.”
“35. In so far as it may justify certain restrictions on the free movement of persons subject to Community law, recourse by a national authority to the concept of public policy presupposes, in any event, the existence, in addition to the perturbation of the social order which any infringement of the law involves, of a genuine and sufficiently serious threat to the requirements of public policy affecting one of the fundamental interests of society.”