THE whole matter is inadvertently summed up by Rosemary Agnew's comment that the Government's interpretation of the law is "very substantially at odds" with her own.

The Information Commissioner was talking about whether Alex Salmond is obliged to comply with a Freedom of Information request (made by the Labour MEP Catherine Stihler) that asked whether the Government had obtained legal advice on the likely position of an independent Scotland in relation to the EU. Her comment applies not only to differing opinions about whether the First Minister is obliged to disclose whether advice has been sought, but also to whatever advice may have been given.

Last week, Jose Manuel Barroso who, as President of the European Commission, takes an interest in these things, said that any new country would have to apply for membership of the EU. These days that means a process which involves the state demonstrating that it is a democracy – an odd requirement, given that the EU itself is demonstrably not one – and agreeing to sign up to the euro, an undertaking about as financially prudent as taking out a 35-year mortgage on Mount Stuart or Culzean Castle at Wonga.com's competitive 4214% APR. (I hasten to point out that you can't; Wonga only offers short-term loans, which is just as well, since at those rates you'd run up more than the US national debt in seven years if you borrowed £100.)

Senhor Barroso was expanding on the case put forward by Olivier Bailly, the EC's spokesman, in response to the position of Catalonia, which has a pro-independence march about this time each year. But, as both men pointed out, it is all slightly speculative and, in any event, not the Commission's province.

This question has been brought up before. Indeed, it was being asked from the moment that the SNP launched its policy of Independence in Europe, during the Govan by-election of 1988 which Jim Sillars won with a swing of more than 38%. I tend to date the modern fortunes of the Nationalists from this period.

At that time, the example most often given – certainly by those who argued that an independent Scotland would automatically remain within the EU – was that of Greenland, which had voted against joining the EEC, and sought to leave when it gained home rule (though not full independence) from Denmark. Because Denmark as a whole had joined, however, there had to be a referendum on Greenland's exit, and the negotiation of a special treaty in 1984.

Europe has changed a great deal since then. The euro hadn't been set up, let alone had time to reveal its inherent and inevitable failings. Nor had the EU progressed so far along the road to "ever greater union", a journey President Barroso is determined to press on with, as he made abundantly clear in a speech a couple of days after his remarks on newly-formed states. Countries such as Norway and Switzerland demonstrate how much better it is to be outside the EU and the euro, but within the European Economic Area, which accounts for why the Eurocracy is so keen to dragoon everyone else into the euro. Someone has to pay for their tax-free salaries and pensions, after all.

One related argument is whether a vote for Scottish independence would actually be about the creation of a new state, or merely a dissolution of the Treaty of Union. If the latter, it might logically be thought to follow that if Scotland needed to apply to rejoin the EU, so would England.

That might be popular with large sections of the English electorate, but it casts the whole referendum in a different light. The argument (which on every other ground seems perfectly reasonable) that only those registered to vote north of the Border should take part in the referendum is at the very least undermined if a "Yes" vote would also take the citizens of England and Wales out of the European Union without their ever having had any say in the matter.

If even President Barroso acknowledges that he isn't entirely sure whether a newly independent state would remain part of the EU or not, I'm not going to attempt to guess. Yet, though I can see that disclosing ministerial advice makes a government's life more difficult, and even have some sympathy with Mr Salmond in his desire to avoid answering the question, it is surely a matter of some importance to have this question cleared up.

If the First Minister hasn't sought legal advice on this issue, then he's been pretty short-sighted. If, as seems much more likely, he has, then his refusal to disclose what it amounted to does rather suggest that he doesn't like the answer he's been given.

Ms Agnew, who seems to be doing no more than her job, may very well be commendably neutral, but one can readily see why opponents of independence are lining up to support her. But even if Mr Salmond has received legal advice which is unhelpful for the cause of Scottish nationalism, he can't simply claim that that makes it "contrary to the public interest" to confirm or deny its existence – even if he thinks the SNP's interest and the country's are one and the same thing.

The consolation for him is that it is only advice. And, as anyone who has ever encountered a lawyer will tell you, advice stating the exact opposite will not be hard to find. But the advantage of this question is that the differing opinions can be tested; they are matters of constitutional law which can be settled by courts and by treaties.

The differing opinions on whether Scotland should be independent or not can only be settled at the ballot box. But the question of how the countries (because it affects all the UK nations) stand vis-à-vis the EU is one which – whatever the diversity of legal opinion – can be settled by the constitutional authorities. It would be kind of useful to have an answer before the referendum, though. Not to have one would be "very substantially at odds" with making an informed decision.