Out of the 15,000 barristers in England and Wales, around 4,000 of us are criminal practitioners, assuming one of these diametric roles in Crown Court (and occasionally magistrates' court) cases across the country. Most of us are self-employed; hired guns, ethically obliged by the 'cab rank rule' to take the first case that comes calling to our clerks, regardless of its merit or our personal feelings about the parties or principles involved. And in crime, this means that most barristers both prosecute and defend (although not, obviously, in the same case). And my view has always been that doing a bit of both is good for the soul. It reinforces your independence. It sharpens your objectivity. And it helps you, in any given case, to know your enemy.