Fortunately at my unit infringements are quite rare (mainly because most of our airspace is well above the normal operating levels of GA aircraft I suspect), however we do get them.
Our first step in the case of an infringement will always be to track down the culprit, using radar monitoring, by speaking to other agencies who might be in contact with the pilot, etc, etc.
Once we know who it is then we'll try and invite the pilot to call us to discuss the infringement. If the pilot doesn't call, then we'll submit a MOR, a CA939 (Alleged Breach of Legislation), and all relevant recordings to the CAA and let them deal with things. We'll also provide an assessment of the impact on civil operations and any safety issues which arose.
If the pilot does call, then we'll let him put his/her side of the story, whilst we'll explain how it was from our point of view. The idea here is that we share the experience and learn any lessons which can help prevent a reoccurrence.
If the pilot is receptive and we get the impression that they have genuinely taken away something which makes them realise the potential (and actual) effect of their actions, plus things which will make them better educated for future flights, then we'll still file the MOR but provide information that appropriate counselling has been given and as far as the unit is concerned, the matter can be closed. We'll also almost certainly forego the CA939 action since the alleged breach of legislation has been dealt with satisfactorily (in our minds) and a prosecution would serve no purpose other than a punishment. Please note that this would generally be for infringements which didn't directly affect safety or cause massive disruption. In those cases, the high profile of the infringement might tie our hands and the CAA will probably wish much more robust reporting and reaction (at least on their part).
If the pilot is non receptive or continues to give the impression they are oblivious to the seriousness of the issues, then our counselling is obviously not working and our only recourse is to take full reporting action and let the CAA deal with it.
At my unit, the majority of infringements are by military pilots, some foreign, but mostly UK air arms. The trainee pilots seem to be the most receptive when discussing the infringement, whilst the steely eyed trained killers seem to try and blame anyone but themselves
