An Englishman went up a hill ...
There's this Englishman walking up a hill - up a mountain actually. Let's say he's from Norwich and that the mountain is Snowdon.
On his way down (having shouted "hey, guess where I am, up Snowdon!" into his mobile) he falls on a dodgy bit of the footpath and injures his leg. When he gets back to Norwich he decides to sue the people whose job it was to make sure the footpaths were well maintained.
He finds that he could use a local Norwich solicitor to bring the claim in a Norwich court, even though he's relying solely on a piece of legislation passed by the Assembly and that has a practical effect only within Wales.
The accident prone walker gets better, then heads off the following year to conquer Ben Nevis. Guess what? He falls. He's not the lucky type. He decides to bring a claim under an Act of the Scottish Parliament but when he gets home to Norwich, he finds that a local solicitor is unlikely to be of much use and that he'll probably be required to travel to Scotland to have his case heard.
There you go - an example (copyright the Welsh government) to tease out what it might all mean if Wales becomes a separate legal jurisdiction.
Shall I be honest? I felt for the poor bloke but it didn't do much for me. It didn't really signal the significance of the question being asked of us. So with apologies to Norwich, let me try it my way.
Since 2006 the Assembly has had the power to make laws. Since last year's referendum it's had the power to make those laws without the need to involve Westminster - laws that are made only in Wales and that affect only Wales.
That hasn't exactly, as the Welsh Conservatives point out today, led to a legislation rush. A single bill on local government bye-laws is "hardly setting the world alight" as they put it.
But that's not to say that there isn't already a body of law that applies only to Wales. Think of the old - banning Welsh pubs from opening on Sundays. Think of the new - banning the use of electric dog collars. Think future plans for changing the laws around organ donation and smacking children. Then consider the Health Bill making its way through the parliamentary process in Westminster - legislation that will apply only in England.
The question then, say legal experts, is at what point does it become more than a bit silly to say there's no such thing as "Welsh law" and no "English law" either come to that - just one law of "England and Wales" ... but that it happens to be different either side of Offa's Dyke? Is that a sustainable point of view?
If you're wondering, it's worth reading this paper by two people who've done more than their fair share of wondering before submitting their evidence.
Carwyn Jones - a former barrister, though not as good a barrister, he reckons, as the current Counsel General Theo Huckle QC - told the Legal Wales Conference last year that "the development of a legal system fit for a healthy and propsperous Wales is vital". It was inevitable, he said, that devolution wold lead to "more distinct Welsh law applying in Wales in future." He doesn't sound like a man prepared to wait for what's been described as a "tipping point" - more in the let's-manage-change and make it happen camp.
Would establishing a separate Welsh jurisdiction lead inevitably to a separate court system?
How would you deal with cross border issues? Could truanting children, for instance, do a Dukes of Hazzard and 'cross the county line' into England to avoid local authority education officers?
Would it lead to lining lawyers' pockets? Or would it, as others have tried to argue, mean less work for lawyers trained in Wales who'd lose out to law-firms in Bristol and Chester, say?
There's support from the Liberal Democrats for asking the question in a public consultation at the very least. "It doesn't make sense" Kirsty Williams told me this morning, "that a matter of Welsh law is heard in an English court ... There is an inevitability about this".
The Conservative response from Westminster: why bother? When you have plenty of problems to deal with in the here and now, why faff around and fix something that isn't broken. "There is no reason to make changes simply for change's sake" says the Welsh Secretary. The language used in private in Westminster amongst her colleagues is more vivid. In Cardiff Bay the Tory line is softer. For now they don't see the need but further down the track, who knows?
Most supportive? Plaid Cymru. "Plaid Cymru has long-campaigned for Welsh control over our crime and justice system in its entirety, including policing and youth justice. Only by doing that can Wales fully tackle the complex problems of individual and community safety and rehabilitation."
And now, here is the Labour First Minister, Carwyn Jones delivering a public consultation into more Welsh control of the criminal justice system. He does realise, doesn't he, that he doesn't need to absorb Plaid out of existence any more, said a Labour voice in Westminster recently. It worked a treat while they were in government. He can stop now.
The 12 week public consultation - well, that starts now.