Earlier this year I read the book
The Chickenshit Club on the advice of someone on here. It has a lot of interesting information but I didn't agree with the author's summary, basically: "prosecutors are cowardly and don't fight cases that don't look easily winnable. They should be braver and go for the highest-profile cases to make a statement". This seems wrong to me because a) litigating a complex, lengthy case and losing is a huge waste of public funds (it isn't a deterrent if the defendants know they can hire expensive lawyers and get off) and b) it can often be counterproductive, since it leads judges to set precedents which make their work harder in future.
One regulatory ideas I thought of was a salary cap on criminal defence attorneys (lawyers can make as much money as they want in civil law, but letting the wealthy hire a different league of lawyers in criminal cases is a huge distortion of justice). This is all more about actual crimes than violating the spirit of the law, but maybe the same could apply to tax law. (I feel like there must be a flaw with this, would be happy to hear what it is.)
(Wrote more about the book here: https://www.goodreads.com/review/show/3507224023)