From the cafe to Cardiff Bay

The colourful cafe in the centre of Cardiff is a big hit with parents who are keen to feed healthy food to their child and "feed your child's mind" at the same time.

Had any of them ever smacked their child?

There was just one part admission, an anecdote of a little boy who'd sat in the middle of the road and a Mum who'd smacked him to save him from from oncoming cars and from far worse.

Otherwise?

Mums and Dads who'd come "this close" many a time, Mums and Dads who think it is simply wrong to smack children "but" ... a Mum who was smacked as a child "and it never did me any harm", carers or nannies who know they simply cannot, in law, smack children, one Dad of Greek descent who simply couldn't believe smacking children hadn't been deemed unlawful years ago, Mums who fear a ban will push smacking - not underground - but the equally fearsome "wait til I get you indoors".

They were sure they felt quite strongly about smacking children. What exactly they thought, though, they weren't at all sure.

That this is an attempt by four AMs, with 9 children between them, to prevent adults who do substantial harm to children from using "reasonable chastisement" as a defence had not got through. As far as these parents were concerned, a smacking ban means that if you're seen giving your child a clip around the ear-hole in the supermarket aisle or at the bus stop, you could get into serious trouble. AMs will this afternoon stress - over and again - that criminalising parents, or labelling them as bad parents, is not the intention of a ban.

It's the comment of another parent, a few days ago, that made me sit up and listen: won't people start thinking, he said, that the only thing that Welsh politicians do is ban things or give them away for free?

Back in the Bay, where the debate is about to get started, there are two more immediate concerns and two parallel conunudrums. The first is the issue of smacking itself. The second is whether the AMs who'll vote on the issue later actually have the powers to introduce a ban.

If you respond to this issue from the stomach/heart, you will care little about the rest of this entry. If you want to engage your brain with the constitutional matters involved here, here's a rough guide to the two sides of the argument care of one who shares your interest.

Does the Assembly have the powers to ban smacking?

The Welsh Government are adamant that the powers are devolved to Wales.

In a letter earlier this month to Christine Chapman, who's leading on today's debate, the First Minister Carwyn Jones says:

"A provision of an Act of the Assembly will, subject to exceptions, be within competence if it relates to one or more of the subjects in Schedule 7. {this is the list of all the fields which are devolved to the Assembly}

"The Welsh Ministers view is that it would be possible for legislation to be passed by the Assembly to make amendments to the criminal law whose effect would be to bring an end to the availability of the defence of reasonable punishment for those cases where it still applies to an offence of assaulting a child."

The subject in Schedule 7 that Carwyn Jones is referring to is number 15 - Social Welfare, which has under it "protection and well being of children".

Welsh Government lawyers would argue that removing the reasonable chastisement defence falls squarely within that field - and therefore the Assembly does have powers to remove it.

Furthermore, they would argue that the devolved settlement does also allow for the creation of new criminal offences in Wales - see the ban on electric shock collars for dogs which carries a potential jail sentence, and the £5,000 fine for shopkeepers who fail to impose the 5p charge for single use carrier bags.

The UK Government has taken and continues to take a very different view. It's all around the definition of the word "relates".

For them, the removal of the defence of reasonable chastisement only relates to the criminal law and nothing to do with social welfare - and so falls under justice and home affairs - which are definitely not devolved.

Giving evidence to the Welsh Affairs Select Committee, the former Under Secretary of State for Wales Huw Irranca Davies said, "a prohibition on smacking would relate primarily to the substantive issue of criminal law as opposed to social welfare fields, and that is where our position remains on this. … we essentially believe that it is an issue of criminal law rather than social welfare."

The chair of the Welsh Affairs Select Committee, David Davies MP, agrees with this view, writing to Welsh Secretary Cheryl Gillan to request that if AMs vote in favour of a smacking ban "the matter is urgently referred to the Supreme Court to ascertain whether the Welsh Government has the legal powers to amend the criminal law."

Mr Davies is slightly jumping the gun here under the new constitutional arrangements following March's referendum. Previously, the UK Government were able to stop any attempt to introduce a smacking ban by refusing to devolve powers over child protection without an explicit exception for a ban.

Now, the situation is different. Were the Welsh Government minded to to introduce a new law banning smacking into the Assembly, and the Presiding Officer agreed with their interpretation that it was within the Assembly's powers, then the UK Government Attorney General would have to wait until an Act had been passed by the Assembly as a whole before he/she could refer it to the Supreme Court who would then decide whether it was within the Assembly's powers.

The legal expert Marie Navarro made an intriguing point on Good Morning Wales that any ban would stand more chance of getting through the Supreme Court if it was rolled up in an Act which made wider provision relating (that word again) to child welfare, rather than a standalone measure making a change to the law.

There is a Children and Young People (Wales) Bill scheduled to be introduced by the Government some time in 2013.

It's important to remember that whatever the outcome of today's vote - it's not binding on the Welsh Government - but it will be fascinating to see whether Ministers vote for, against, or abstain in the vote this evening.