Re: They dont want to use the MLAT.
Except it's not illegal, and the request in question is a fairly trivial "rubber stamp" exercise IIRC it's relating to drug dealing/trafficking. In fact, it's such a straight-forward request the whole thing is highly suggestive that the data in question isn't the real purpose of this exercise.
AIUI the Irish government, in their brief reminding the US courts that Ireland is a sovereign state, made the point that this specific case met the requirements for an MLAT request with relative ease. This is about establishing a precedent, with a case no one thought MS would actually fight. MS managed to get the media to focus on the extra-territoriality of the case and not the detail that "They were helping drug-dealers".