Now that Article 50 has been triggered and the Great Repeal Bill white paper published, the intensive discussions with the devolved administrations promised by UK Government should to begin. Richard Percival assesses the tricky legal road ahead for the Government if it is going to succeed without damaging Brexit plans, the Union and the constitution.

The Government is in a bind over Brexit and devolution, and there is no pain-free way out of it.

The main problem is that devolution was developed under the umbrella of the EU single market. This meant that there was no need for the devolution settlements to make provision to preserve an internal UK single market.

Rather, the devolution Acts simply said that the devolved institutions had to obey EU law; and EU law ensured the existence of the single market. As a result, the devolution Acts could devolve large areas of policy to the devolved countries, on the assumption that what was being devolved was only the UK end of a Brussels dominated legislative domain.

In particular, agriculture, fisheries and environmental protection are all devolved in each of the three settlements. The Government believes that the fundamental framework, previously set at the EU level, must now be set at a UK level to retain the single UK market for domestic reasons, to avoid, for instance, Scotland adopting a different regime for subsidising agriculture so that Scots farmers could secure an advantage in the food market. The Government also needs this control to effectively negotiate free trade agreements internationally.

For current purposes, it does not matter whether either of these things is true – it is what the Government thinks.

What the Government seems to have only recently fully realised is that to accomplish these ends, it has to legislate to change devolution.

In policy terms, the Common Agricultural Policy has been the means by which farm subsidies have been decided for decades. If we leave the EU, that policy is “repatriated” (to use the Government’s terms), and the decision is whether this new area of policy responsibility should fall to the UK Government or the devolved administrations. This perspective is clear in the devolution chapter in the UK Government’s recent white paper on withdrawal from the EU.

But the devolution settlements turn policy areas into legal categories, and “agriculture” is devolved. So if the UK Government wants what Brussels used to do to come to the UK Government, it will need to change the law.

The Sewel convention

And the problem from the UK Government’s point of view is that the Sewel convention dictates that such a change requires the consent of the devolved legislatures. The convention, as originally formulated in 1998, stated that the UK Parliament will “normally” not legislate in devolved areas without the consent of the relevant devolved legislature.

That is now known as the first limb of the convention.

The second limb is that the UK Parliament will not legislate to change the powers of the devolved institutions without similar consent, which came about as a result of a perceived loophole in the devolution settlement in connection with changes to competence. There is provision in the devolution Acts to allow changes to competence to be made by an Order in Council (a superior kind of secondary legislation), but that order-making power is subject to motions of approval in the devolved legislatures. The original scheme of the legislation, therefore, was that changes to competence should be made via this power.

However, it became apparent that tweaks to competence would be necessary in primary legislation, as they related to the subject matter of that legislation. Accordingly, the UK Government’s “Devolution Guidance Notes” were amended to add the second limb. It is in this form that the convention appears in the Standing Orders of the Scottish Parliament and the National Assembly for Wales.

It is possible that the Government might argue that, strictly, the convention only covers the first limb. But it is a difficult argument – and even if Sewell is confined to limb 1, there is a strong argument that limb 2 should still be considered a distinct constitutional convention.

Where it applies, the convention requires the devolved legislatures to pass Legislative Consent Motions to approve the relevant UK Parliamentary legislation.

The obvious way to change the devolution settlements would be to give those powers actually exercised in Brussels to the UK Government.

But this is not straightforward technically. For legislation to distinguish between the elements within the policy/legislative fields of agriculture, fisheries and environmental protection, which the UK Government wants to exercise centrally is very difficult. The terms used to describe reservations are either very broad, “the currency”, “immigration”, or they relate to specific instruments, “the subject matter of the X Act”. Neither of those techniques is going to work well for the CAP, or Common Fisheries Policy.

They would also need a Legislative Consent Motion, under the Sewell convention second limb. The Scottish Government has made an art of extracting concessions as the price for a Legislative Consent Motion and Welsh Government can claim that they obtained what they see as an acceptable financial framework agreement as the price for the Legislative Consent Motion to what is now the Wales Act 2017 earlier this year.

But it’s hardly plausible that the UK Government could find acceptable concessions for something as big as this.

It is pretty obvious what the Scottish Government’s demand would be – the second independence referendum – and conceding that would surely impose too high a political cost on the Prime Minister. The Welsh Government might be easier to appease, but that is no solution for the UK Government if it can’t solve Scotland.

These technical difficulties could potentially be overcome if the UK Government took an alternative tack.

For example, instead of looking to broad reservations to clear the field for the detailed UK-wide frameworks in agriculture, fisheries and the environment, they could set out the framework in legislation first, and then make the changes to the devolution settlement.

We know that substantive Brexit bills are expected in each of these areas. The plan is presumably for these bills to set out the UK single market framework that the UK Government wants. They will work at a reasonably detailed level, so could be drafted to demonstrate that they would only encompass the decisions previously made in Brussels. The read-back into the devolution Acts (which would be in the same legislation) could then be limited to the reservation of “the subject matter of the Environmental Protection Framework Act 2018”, and similarly for the other areas.

The Government, however, would still need a Legislative Consent Motion – and indeed, that the convention applied would be unarguable, given that this would be a first limb situation. So the Government’s fundamental problem remains.

A fundamentally new approach?

Could the UK Government change its fundamental approach, and seek a co-operative outcome with the devolved institutions?

Theoretically that might be the most attractive outcome. Some have floated the idea of a “Council of the UK” composed of representatives of the four governments, much like the European Council in the EU constitution. However, it is unlikely that UK Government would agree to an institution in which it had one vote amongst four.

A framework powers model on the other hand could be made workable, with good will. For instance, if the four governments negotiated a framework in each policy area based on that inherited from the EU, the result could be encapsulated in a UK Act to which each of the other legislatures would consent.

The quid pro quo for such agreement would be that there was no change to the devolution settlements in that the broad powers currently devolved would be retained by the devolved institutions. They could in theory therefore, legislate to take themselves out of the framework – but on this scenario, they would be locked in by mutual agreement, rather than force of law.

However, with little good will particularly between London and Edinburgh this would seem implausible. It is difficult to see the incentive for a Scottish Government seeking to secure independence on the back of a chaotic Brexit to cooperate in a consensual effort to mitigate the damage using UK mechanisms. And equally difficult to imagine the UK Government trusting the Scottish Government to do so, even if it appeared willing. That there isn’t even an administration in Northern Ireland to negotiate with doesn’t help. Such an approach might appeal to the Welsh Government, but that is not enough.

There is yet another possible road for the UK Government. The Sewel convention may be a constitutional convention, but it is only a convention. It is politically recognised as voluntarily binding as a constitutional matter, but it is not legally enforceable. The fact that it is now recognised in legislation (although the legislation only sets out the first limb) does not change that, as we now know from the Supreme Court decision in Miller.

The Government could, in other words, use the hardest bit of the hard constitution – the sovereignty of Parliament – to force through changes to both the substantive law and the competence of the devolved legislatures. In the context of the convention, they could even claim that they were not breaching its express terms: it says “normally”, and these are not normal times.

It might come to that. But if it did, the UK Government would be handing arsenals full of political ammunition to the nationalist in Scotland and – although it will worry them much less – in Wales. An assault on the soft constitution of devolution of this sort might also have incalculable effects in Northern Ireland (although the effects of Brexit on Northern Ireland seem to have had rather low visibility to the UK Government so far).

The sparse chapter on devolution in the UK Government’s white paper sets out the issue, but as to an answer, goes no further than to commit them to “intensive discussions with the devolved administrations”.

Whatever is said, barring a sudden and unprecedented outbreak of mutual confidence and respect, it does not look like the UK Government can get what it wants without damaging its Brexit plans, the union, the constitution, or all three. And it is the UK Government who must make the first move.

This post represents the views of the author and not those of the Welsh Brexit blog, nor Cardiff University.

Richard Percival, Senior Research Fellow, Cardiff School of Law and Politics and member of Wales Governance Centre.