I recently read Jon Ronson's brilliant book, The Psychopath Test (I say "read", I actually just listened to Jon reading it out on my daily trudge to RoF Towers). It's terrific, if a little gruesome at times. I love his fey Northern tones and his general cleverness. And his absolute brass balls when it comes to talking face-to-face with psychopaths.

It turns out that psychopaths are pretty easy to spot. All you need to do is go on a three day course run by Robert Hare, a Canadian psychopath-spotter and inventor of the Hare Psychopathy Checklist. It's a personality quiz which you can apply to anyone to work out if they're psychopaths. If they are, there's no cure, and they need to be locked up for the rest of their lives.

What's this got to do with law? Well, it seems that whilst only about 1% of the general population is a psychopath, when it comes to business leaders, CEOs, top politicians and the like, that proportion is quadrulpled. So how would top City partners come out when the Hare Checklist is applied? It's not as simple as you might thing. If they all regularly slammed axes through the heads of their business associates during a lecture on Phil Collins, or kept the fully-dressed corpse of their mother in a rocking chair, it would be easy. The Hare Checklist is a bit more subtle. Over an excellent and extensive lunch, the RoF Team totted up some scores, reckoning that whilst some of the charateristics clearly (hopefully) don't apply - the dishonest thieving and so on - we each knew partners to whom many of the categories applied. Now it's your turn.

It's a 20 question checklist. For each component, score either 0, 1 or 2 for the partner of your choosing. If they score more than 30 (or as low as 25, for a UK diagnosis), they're clearly a psychopath and should probably be in Broadmoor for the rest of their lives.

Here are the characteristics to measure against (which I've pinched from the font of all wisdom):

Factor 1: Personality "Aggressive narcissism"
Glibness/superficial charm
Grandiose sense of self-worth
Pathological lying
Cunning/manipulative
Lack of remorse or guilt
Shallow affect (genuine emotion is short-lived and egocentric)
Callousness; lack of empathy
Failure to accept responsibility for own actions

Factor 2: Case history "Socially deviant lifestyle".
Need for stimulation/proneness to boredom
Parasitic lifestyle
Poor behavioral control
Lack of realistic long-term goals
Impulsivity/Irresponsibility
Juvenile delinquency
Early behavior problems
Revocation of conditional release

Traits not correlated with either factor

Promiscuous sexual behavior
Many short-term marital relationships
Criminal versatility
Acquired behavioural sociopathy/sociological conditioning (i.e. a person relying on sociological strategies and tricks to deceive)

So pick your favourite partner, and judge them against these criteria. There may be an element of artistic licence involved (I've fantasised that many of my former partners enjoyed picking off butterflies' wings - although that fantasy probably makes me a psychopath). And if you've uncovered a psycopath at your firm, please do not write in and tell us about them. It's probably highly defamatory. And who would want to defame a psychopath?

NB if, after applying the checklist to your favourite partner, you're worried about being a psychopath yourself, have no fear. Brilliantly, anyone who is scared that they might be a psychopath, definitely isn't. Now isn't that a relief?