However, within hours of making the attack, Mr Russell had retreated, saying the experts were in fact not a kangaroo court while the Scottish Government issued a statement – insisting his retraction drew a line under the matter.
The forum in Edinburgh was organised by Lord Wallace, the Advocate General, who has argued that, thus far, the Scottish Government has failed to provide credible answers to key questions on the country's future were it to become independent.
The objectivity of the forum was called into question when Mr Russell tweeted: "Yet another kangaroo court masquerading as 'impartial' – farcical."
The legal experts included Austin Lafferty, President of the Law Society of Scotland, and Richard Keen, QC, Dean of the Faculty of Advocates, who successfully defended one of the men accused of the Lockerbie bombing.
Liam McArthur, the Scottish Liberal Democrat Education spokesman, attacked Mr Russell's broadside.
He said: "It is incredible that Scotland's Education Secretary deems it appropriate to attack eminent and respected lawyers and professors.
"Scotland's academic community will rightly be disappointed that their own government minister has attacked their integrity in such a cheap and public way.
"Mr Russell should spend more time ensuring the Curriculum for Excellence is a success and less time launching such schoolboy attacks."
After critical online responses to Mr Russell's comments, the Education Secretary retweeted, saying: "To be clear – the experts involved are not a 'kangaroo court' but there can be no faith in conclusions drawn by Jim '#Iamthelaw' Wallace."
Last night, a spokesman for the Advocate General said: "It is pretty surprising that the Minister responsible for Scottish education is spending so much of his time criticising senior Scottish legal figures for discussing independence.
"It seems once Mr Russell realised the calibre of those involved he came to the view that this would be a very eminent kangaroo court. He has taken to Twitter again to clarify his remarks and it is probably best just to leave it at that."
Meanwhile, a Scottish Government spokesman said: "The Cabinet Secretary has made his position perfectly clear that these experts are not a kangaroo court and, therefore, this draws a line under the matter."
In a separate development, the Scottish Trades Union Congress announced a series of public events to discuss Scotland's constitutional future but warned party-political wrangling risked stifling debate on the subject.
Grahame Smith, the STUC's General Secretary, said the organisation was "deeply concerned" party political rows might "strangle proper issue-led discussion".