The order isn't against any person or entity in Ireland. It is against a US company, and US employees, who can access the data from their desks in the US. Under US law, it is certainly a valid order. Under Irish law, it is not. There is a conflict that the US prosecutor (and judge) do not want to (or can't, under current law) address. No matter what Microsoft does, they will break the law somewhere.
This is a surprisingly (for the source) thoughtful account of things so far, and explains the reasoning behind the order.
I doubt you will bother to ready it, and likely won't understand it if you do, and certainly won't care, but there it is.