By Eric King-

The dispute over the Article 50 trigger, which the High Court has ruled must require the permission of Mp’s has started another political exchange of words between the UK government and the Welsh government.

An appeal of the High Court ruling that Parliament must vote before Article 50 can be triggered, begins tomorrow, Monday. It will go into all the legal arguments of this case.

The Welsh Government’s counsel general Mick Antoniw has asserted that beginning the process without MPs’ consent would change Wales’ devolution settlement.

The UK government has accused him of trying to get judges to interfere with processes typically confined to political judgement, rather than ”legal adjudication”.

According to their argument,  U.K Prime Minister Theresa May can use the crown prerogative to invoke Article 50 of the Lisbon Treaty. Under the powers of the crown prerogative, ministers do not require the permission of MPs to start a legal process.

Arguments of law are often very debatable, depending on how they are argued and how much room different legal principles allow for their implementation.

 The Welsh Government’s top legal advisor, Mr Antoniw,disputes this and argues that starting this process would “modify the competence of the National Assembly for Wales and the Welsh Government”.

He said triggering Article 50 without the permission of Parliament would “short-circuit” a rule – called the Sewell Convention – one that prevents ministers in Westminster passing laws on devolved matters without the consent of Welsh ministers.

The outstanding lawyer told BBC’s Sunday Politics Wales programme that the UK government’s argument that it did not need MPs’ permission to start the process was “very imprudent”.

“It does not impress, and I’m not certain it will impress the court either,” he said.

“Because if you have a strong argument you don’t need to use that type of language; the strength of your argument is in your case itself.

“So, for me, it sounds as if it’s becoming a little desperate.”

The UK government insist that Mr Antoniw and his counterpart in Scotland are asking the Supreme Court judges to stray into “areas of political judgement rather than legal adjudication”.

Downing Street told the BBC that the court must resist that invitation, ”particularly where the underlying issue is one of considerable political sensitivity.”

According to Downing Street, the Sewell Convention would not be “short-circuited” because it is “a political convention” not a “justifiable legal principle”.

Legal principles, not political conventions, are the basis of legal arguments but any effects on political conventions will not be totally ignored by the Courts.

The Welsh government will argue firmly that the government must not trigger Article 50 without permission of Mp’s. Wales voted to leave the EU, but it seems the Welsh government is more concerned about the process and form Brexit takes. If this is their true concern, it assumes they will oppose a blanket opportunity for MP’s to overrule Brexit. The issues of devolution ranks high in their consideration.

The Supreme Court, being the highest court in the land, will have all 11 judges on the panel in a four-day hearing and will deliver their verdict in January.

Complicating the dispute even further is the fact that Welsh secretary Alun Cairns is not on the side of the Welsh Government. Cairns suggests that the Welsh Government may be trying to frustrate Brexit in its involvement in the Supreme Court appeal.

Doing so would provide “greater uncertainty”, he said, insisting  that the case from the Welsh Government is on a very narrow area.

“It’s only right and fair that they put that in front of the Supreme Court.

“But I hope it’s been taken in a positive way rather than in a way of frustrating the process.

 Wales voted to leave the European Union, and Carns wants to see the process of Brexit completed smoothly. Carnes told the BBC:

“So I hope it’s not being used as a chance of frustrating the process for the whole of the United Kingdom – and that will provide greater uncertainty.

“We are providing the greatest certainty possible by saying that we will invoke Article 50 by the end of March, and we are still planning on working to that timeline.”