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 today 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.