More than three years after the Labour MEP Catherine Stihler first raised the question of Scotland's membership of the EU in the event of a vote for independence, there is still more darkness than light on the issue.

Now the European Parliament has announced it will be seeking legal advice in an attempt to resolve the question once and for all.

The Scottish Government's position has always been clear, even if it has sometimes been a case of assertion more than fact. According to the SNP, a newly independent Scotland would negotiate its membership of the EU from within the organisation using Article 48 of the Treaty on European Union. The whole process, according to the Scottish Government, would take around 18 months.

The UK Government rejects this and insists an independent Scotland would have to apply for membership in the way that any other new member must, using Article 49, and it has some support for that position from Jose Manuel Barroso, president of the European Commission. The UK Government also says that, far from taking a mere 18 months, Scotland's application for EU membership via Article 49 is likely to take much longer.

The obvious way to try to resolve this argument is to seek legal advice as the European Parliament is now doing but, until now, any attempt to find legal clarity has failed. First of all, there was the debacle of the Scottish Government fighting to keep secret legal advice that never existed in the first place, but the greater problem has been that lawyers simply disagree on the matter.

Earlier this year, for example, a number of eminent lawyers appeared before the European and External Relations committee at Holyrood to give their view. Some of them agreed with the UK Government that an application through Article 48 was implausible, but the former European judge Sir David Edward said Scotland's membership could be achieved through some relatively small amendments to the existing treaty.

As far as possible, this uncertainty needs to be cleared up before the referendum, not least because how Scotland negotiates its EU membership in the event of a Yes vote raises important questions about its economic fortunes. The most important of these questions is: if an independent Scotland came to apply to join the EU, would it be likely to lose its share of the UK budget rebate, which is worth many billions of pounds a year? It is a worrying prospect for the Scottish Government, with huge economic consequences for an independent Scotland.

The European Parliament's decision to seek advice may bring some clarity on all these questions, although it is unlikely. Ultimately, the decision on whether an independent Scotland has to apply using Article 48 or Article 49 will be a political rather than a legal one and the uncertainties there are just as great. Spain, for example, has already indicated it feels Article 49 is more appropriate but would it still take this view when the time came? No on can know the answer to that, which means that clarity, though desirable, is still just as far off as it has ever been.