Bombarded by demands for clarity on the issue from politicians in the UK and Spain, MEPs have sought a formal opinion from their own lawyers.
Their decision will be a major test of the legal robustness of the Scottish Government's view - shared by some experts but rejected by others - that it can seamlessly join Europe in a quick treaty amendment under the so-called Article 48.
It comes as Prime Minister David Cameron, who believes Scotland would have to apply for membership as a new state under another EU Treaty article, Number 49, will today urge the English, Welsh and Northern Irish to "lovebomb" Scots with memories of shared Olympic glory.
He is expected to be joined at London's Olympic Park by athletes competing in this year's Commonwealth Games in Glasgow.
He will say: "The best thing about the Olympics wasn't the winning. It was the red, the white, the blue. It was the summer that patriotism came out of the shadows and into the sun. Everyone cheering as one for Team GB."
The SNP has accused Mr Cameron of a "tawdry" bid to politicise a sporting event.
The European Parliament's legal advice has been formally sought by the chairman of its Constitutional Affairs Committee, an Italian Conservative called Carlo Casini. It is expected to be available in time for his committee's final meeting next month before the parliament breaks up.
Scottish Labour MEP David Martin, who shares Mr Cameron's view on the process for EU membership, said last night: "This will be an authoritative opinion. I am hoping we get it in the next two weeks.
"I am firmly of the view that Article 48 is not a goer and that the Scottish Government has come up with it because it wants to pretend there is a continuity of membership."
However, Alyn Smith, an SNP MEP and EU lawyer, said the Scottish Government was relaxed about the coming European Parliament opinion.
He said: "We are confident that the reasonableness and mutual self-interest set out in the White Paper on independence will win through. This, however, will be one opinion among many."
The Scottish Government has never formally asked the European Commission for a firm legal view on what legal experts called "internal enlargement", the membership of territories of existing member states.
The SNP says this would be a matter for the UK Government, which is the member state. It, in turn, has failed to make inquiries.
Some governments have signalled unease at the prospect of Scotland fast-tracking to the EU. Spanish Foreign Minister Jose-Manuel Garcia-Margallo this week repeated the statement that his country would not veto Scottish membership. However, he added that an independent Scotland would have to "join the waiting line and ask for admission".
The Spaniards are desperate to flag up EU membership problems for Catalans campaigning for independence.
Last week one expert, Kenneth Armstrong, said France and others could see any attempt to use Article 48 as "a Trojan horse" that could open up the EU treaty to secure the radical changes Mr Cameron wants to the UK's membership ahead of his planned 2017 in-out referendum. However, some Brussels watchers think too much weight has been put on the legal niceties of EU membership after independence.
Professor Michael Keating, director at the Economic and Social Research Council's Scottish centre on constitutional change, said: "I think either Article 48 or Article 49 would work. I don't think it is a legal question. I think it is a political question. The member states can do whatever they like.
"If there is a will to get Scotland in the EU, it would simply be a question of which is the most convenient way of doing it.
"For what it is worth, I don't see any political will to exclude Scotland from the EU.
"It isn't in the interests of any of the member states, including the UK and Spain."
Mr Keating earlier said an independent Scotland would struggle to make its voice heard within the EU if it made no attempt to join the Euro.
In written evidence to Holyrood, he said large states enjoyed more influence in the EU, but smaller members could wield influence by coalition-building.
However, he said the SNP's plan to keep the pound and negotiate a share of UK's budget opt-out would align an independent Scotland with the Eurosceptic UK and "weaken its capacity for influence".