A full hearing in a dispute surrounding the status of an independent Scotland in Europe will be held at the end of the year after a judge ruled the matter could be dealt with urgently.
The SNP insists that an independent Scotland would automatically be accepted into the EU, while opponents say it would have to reapply and lose the UK's existing rights and opt-outs.
Information Commissioner Rosemary Agnew wants the Scottish Government to say whether or not it has received any legal advice on the issue.
But First Minister Alex Salmond said disclosing whether they hold the information would breach the ministerial code and they are appealing against the commissioner's ruling.
Ms Agnew went to the Court of Session in Edinburgh to seek a speedy disposal of the case.
Lord Menzies fixed a two-day court hearing for December 18 and 19 after hearing both parties were content with those dates. "I shall approve of this matter as suitable for urgent disposal," he told the court.
The Scottish Government wants to hold a referendum on independence in the autumn of 2014.
The current legal wrangle comes months after Labour MEP Catherine Stihler tried unsuccessfully to get the Holyrood administration to reveal any legal advice it had received about Scotland's future in Europe.
In July the Information Commissioner ruled that the Scottish Government failed to comply with legislation by refusing to disclose whether legal advice was taken on the issue. She told ministers to confirm or deny whether they hold the information but stopped short of ordering the actual release of any advice.
The Scottish Government subsequently launched an appeal against the request at the Court of Session. Ministers are said to be spending £100,000 to defend their claim that they do not have to tell the public whether they took legal advice on an independent Scotland's future in the European Union (EU).