He researches tax dodging. He is probably the foremost authority on taxdodgers, and as a result is hated and attacked by them at every opportunity.
There are two answers to your second question. People working for tax dodgers will say that one's legal and one's illegal, and anything that's legal is by definition right and proper.
People not working for tax dodgers will say that the boundary between legal and illegal taxdodging is false and in any event frequently breached, and that taxdodgers lie and cheat to manipulate their returns so they appear to have avoided and not evaded tax.
Me. I say it's all the same pack of cards, and we need to get tough with these people. Take that tax, close them down, prosecute them like we do "benefit cheats" (though tax dodgers cost us far, far more money).
OK thanks, the only thing I dont get on this Murphy chap is on that link it says that tax avoidance is about £70m but on checking him he is an advisor to the TUC and yet they only quote £12bn, surely it would be in their interest to quote his higher figure. I do agree though that tax avoidance/evasion costs more