When all solutions are bad, it’s time to reinvent the problem. Is it still possible to honour the initial Brexit referendum without crossing the EU’s red lines? Yes – through semi-Brexit.

The UK is divided into four nations, two of which voted remain and two of which voted leave. The British government could honour those decisions and allow Scotland and Northern Ireland to remain in the EU as the successor state to the UK, while permitting England and Wales (if it still wants to) to exit.

Semi-Brexit does not mean breaking up the UK. Rather the reverse: semi-Brexit may be the only way to hold the UK together. If the UK drags Scotland and Northern Ireland out of the EU, the chances of a UK breakup are much higher. But if Scotland and Northern Ireland remain, then England and Wales would have more flexibility to negotiate a better deal. Third states – that is, states outside the EU – cannot cherry-pick the bits of the EU that they want and reject those bits they don’t. But parts of EU member states that are otherwise outside the EU can.

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At least 35 countries and territories already have special deals with the EU that include, for example, free movement of goods into the EU without triggering the free movement of EU nationals back. Or deals that include something close to free trade without the jurisdiction of the European court of justice (ECJ). And on and on and on. The combinations of inside-EU privileges with extra-EU independence are very nearly endless. And they already exist.

There’s just one catch: the territories that get to cherry-pick from the EU in these ways must remain constitutionally attached to a current EU member state. From “outermost regions” (nine of them) to “overseas territories” (25 of them) to bespoke agreements with the EU on the part of special regions (a half dozen or so), far-flung – and not so far-flung – territories have worked out special arrangements with the EU through their associated member state.

One does not have to look far to see how. The Isle of Man has free trade with the EU for agricultural and manufactured products but is otherwise not bound by EU law. Guernsey has free trade in goods more generally, but no EU nationals have free movement rights into Guernsey. In fact, the array of models one could use for a bespoke deal for England and Wales is nearly endless. But getting these options requires part of the UK to stay in the EU.

Facebook Twitter Pinterest ‘The Isle of Man has free trade with the EU for agricultural and manufactured products but is otherwise not bound by EU law.’ Photograph: benkrut/Getty Images/iStockphoto

How would this be possible? The EU law questions are relatively easy while the heavy lifting, legally speaking, falls to UK constitutional law. The ECJ has just held that the UK can halt article 50 unilaterally. By doing that, the UK could put its negotiations with the EU on a different track.

Of course, the EU wouldn’t tolerate an open-ended Brexit process wreaking havoc with long-term planning. The EU would have to know soon how to figure the UK into its parliamentary election cycle in 2019 and new budget cycle shortly after that. If, however, the UK were to announce that Scotland and Northern Ireland were staying in the EU while England and Wales exited, then the number of MEPs the new UK should elect in the new European parliament follows a formula. Ditto with the budget contribution. With these adjustments, the EU could go ahead and plan its future.

Once the UK’s parameters in Europe were settled, the EU could begin negotiations with England and Wales over a new long-term relationship. The EU framework for special territories has no draconian deadlines – by contrast with the short deadlines of article 50.

The harder transitional questions fall in UK constitutional law. The Westminster parliament would have to give the four nations the power to make international agreements in their own name so that each could remain a member of the EU (or not) separately. All subject areas covered by EU law would have to be devolved from Westminster to the four nations so that they could ensure harmonisation of their laws with EU law (or not).

In the current UK constitution, however, the four nations are not equal: England would have to acquire its own parliament to receive the devolution. This idea has been well mooted already so plans are already available. In fact, the creation of an English parliament would bring self-government home even more dramatically than Brexiteers promised.

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Beyond that, there are questions about how to organise borders for whatever would not flow freely between the EU and the part of the UK that left. To control the flow of people, England and Wales could require residency and work permits for foreigners who live and work on its territory while the part of the UK that remained in the EU would allow free movement. UK corporations that wanted the benefits of EU status could reincorporate in Scotland while keeping their current offices in London – and charging a reasonable reincorporation tax would float Scotland’s budget again.

In semi-Brexit, England and Wales might be able to negotiate free movement of exports under arrangements similar to those of the Channel Islands. If the EU were unwilling to go that far, however, arrangements for the movement of goods would, under this proposal, at least be displaced from the fraught international border between the UK and Ireland to the less-fraught borders between England and Wales and the rest of the UK. Without the pressing March deadline of article 50, these questions could be resolved in their own time. Perhaps Northern Ireland could even form a government by then.

If England and Wales wanted one day to get back into the EU after semi-Brexit, re-entry would be easier than if the whole UK left. A single unanimous vote of the European council is sufficient for re-entry. In the process of re-entry, England and Wales would not lose all of their special agreements and opt-outs because the remaining UK would retain them.

With semi-Brexit, the UK could honour the referendum and allow each part of the UK to get what it voted for. Semi-Brexit would also give the EU a graceful way to provide a better deal for England and Wales. Isn’t semi-Brexit, then, the least worst path forward?

• Kim Lane Scheppele is the Laurance S Rockefeller professor of sociology and international affairs at Princeton University