He said legal reforms inspired by the American system of "vicarious liability" would make it easier to hold banks and other large corporations criminally responsible for wrongdoing carried out by their staff.
"My real worry, and why I think the law should be changed, is public confidence," he said.
"The public look at the perceived American performance against corporates and they understandably think, 'Why can't this country do that?'
"The answer is that American prosecutors have far more power than we do. Over there, if someone is acting criminally in the course of their employment and part of their motive is to benefit the company then anything they do makes the company liable. That's very easy.
"Here, we have the 'controlling mind' test where if you want to convict a company you have to prove that the 'controlling mind' — usually the board of directors — was complicit."