On Thursday the people of Scotland will be told the date of the independence referendum to be held in autumn next year. One of the major issues weighing on voters' minds will be whether the new country would remain a member of the European Union, or have to leave and "join the queue" to be readmitted.

There is one body – the European commission, the "guardian of the treaties" – that could easily answer that question. But instead, under the pretence that this would be "interfering" in the UK's internal affairs, the commission is deliberately obfuscating. Worse, by implying (quite wrongly) that some law exists that would prevent Scotland from negotiating membership in the months or years between a referendum and actual independence, it is in fact blatantly interfering in the referendum debate, by sowing doubts about an independent Scotland's future.

Take the remarks made by the president of the commission, José Manuel Barroso, last December, which were greeted with jubilation by anti-independence campaigners. Barroso's view that a newly independent state would have to renegotiate entry into the EU was reported as a "bombshell". This was the final word, from the horse's mouth. The BBC's Europe editor even opined that "under EU rules" Scotland's application to join "would be hard". Steve Bell drew a cartoon showing Alex Salmond caught with his EU pants around his ankles.

Nobody stopped to analyse what Barroso had actually said. I have spent the best part of three months chasing the European commission to explain to me whether his words were merely his opinion, or whether they had some basis in EU law. The answer – inasmuch as the commission's finely crafted stonewalling can be termed an answer – is that, in legal terms, what he said was bunkum.

Barroso was asked whether the commission could confirm the "view" (sic) expressed by his predecessor Romano Prodi in 2004, to the effect that "a newly independent region would become a third party with respect to the Union and the treaties would, from the day of independence, not apply any more on its territory". Yes, replied Barroso, he could confirm this because "the legal context has not changed since 2004 as the Lisbon treaty has not introduced any change in this respect".

Alarm bells should have clamoured in the ears of everyone with the slightest knowledge of the EU. Of course the Lisbon treaty did not change the legal context regarding this issue – because the Lisbon treaty has nothing whatsoever to say on the matter! Lisbon deals with many important things (including how a member state might withdraw from the Union), but not the question of what happens with a region that secedes from an EU state. It's like saying, your gas bill has not been affected by recent changes to the mobile phone network. True, but daft.

So why did he say it? In letter after letter to the commission I have pleaded with them to spell out to me what "legal context" Barroso was referring to. Which treaty article or EU law did he have in mind? No reply.

I asked whether Prodi's "view" (the thing that Barroso confirmed) had any legal status, or was it really just his opinion. Again, an eloquent silence.

I asked them to confirm that in fact there is no provision in EU law to deal with the situation that will arise if part of a member state secedes. No reply.

I put it to them that in such a circumstance, the member state itself would have to renegotiate its membership terms (number of seats in the European parliament, votes in the council, contribution to the budget etc), and that during that period of negotiation it would surely be possible for the seceding territory (prior to its actual declaration of independence) simultaneously to negotiate its own terms of membership. No reply.

The commission, I was told, "will only be able to express its opinion on the legal consequences under EU law of a specific situation upon request from a member state detailing a precise scenario".

Why? It is the European commission's job to interpret EU law. That's what it exists for, and it does it every day, without being prevailed upon by member states. And yet in this historic situation it refuses to clarify to the Scottish people what a vote for independence would actually mean. Instead, it uses weasel words patently designed to influence the vote.

If it were honest, it would surely admit that there is simply no precedent, and nothing in EU law, that would preclude a territory that has voted for independence from negotiating its continuing membership together with the "rump" state. That would be a truly neutral position for the commission to adopt, rather than scaremongering and baffling people with references to a Lisbon treaty that in this context is totally irrelevant.

My own guess, having followed dozens of EU summits, is that an independent Scotland's membership terms would be negotiated in a long night of whisky-fuelled Brussels bickering. The objections to independence from third countries would wither away once voters had actually said "yes", because the priority now would be to avoid the catastrophe (for the EU) that would ensue if at the stroke of midnight on independence day Scotland were suddenly cut adrift.

Why would Spain wish to kick Scotland out, thereby banning its own trawlers from Scottish waters? What would any other country gain by making Scotland leave, wait a while, and then rejoin? Out of sheer self-interest every other country would want to avoid such pointless disruption. Moreover, EU law is already embodied in Scots law, so there would be no complex "accession process". Far from being "hard", or having to go to the "back of the queue" (what, behind Turkey?), Scotland's accession would almost certainly be the smoothest and quickest in EU history. There will be plenty to argue over in the next year and a half, but Scotland's place in Europe should not be one of them.