Solicitors acting for the Good Law Project and Molly Scott Cato, MEP have written  to the Department for Exiting the European Union and HM Treasury asking for their release. Unless the studies are provided within 14 days the Good Law Project and Ms Scott Cato will issue judicial review proceedings to attempt to force the Government to publish them.
Two classes of document are being sought.
First, those mentioned by David Davis MP to the Commons Committee on Exiting the EU on 14 December last year: “our 57 studies cover 85% of the economy—everything except sectors that are not affected by international trade” . DExEU has repeatedly promised to publish a list of studies “shortly” but has not yet done so . And, second, a report prepared by HM Treasury comparing the predicted economic detriment of Brexit with the predicted economic benefits of alternative free trade agreements.
Good Law Project founder, Jo Maugham QC said:
“This is our Government, it must act in our interests, and we must be able to see that it is. Scrutiny lies at the heart of our democracy and these studies inform decisions having a profound impact on our futures.
“There is a clear and compelling public interest in their production. It is not right that they be hidden from public view. We must be able to see what Brexit means.”
Molly Scott Cato MEP said:
“The European referendum was all about taking back control but how can we know if our democratic representatives are making decisions in our interests when the government is withholding vital information? It has been clear for some time that the attempt to keep the Brexit impact studies secret is more to cover the government’s blushes than to enable efficient law-making. The rule of law requires that MPs know what Brexit really means before they formally vote on whether we withdraw.”
The Good Law Project  and Molly Scott Cato are being advised by Tim Pitt-Payne QC and Robin Hopkins each a leader in the field of information law. They are instructed by Constantine Partasides of Three Crowns LLP.
The Good Law Project is also launching a crowdfunding campaign to fund the costs of the judicial review proceedings. 
1. The letter can be seen here: https://www.dropbox.com/s/fy3ladlqey5def8/LettertoDExEU.pdf?dl=0.
2. See http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/exiting-the-european-union-committee/the-uks-negotiating-objectives-for-its-withdrawal-from-the-eu/oral/44457.pdf.
4. The Good Law Project is a not for profit founded by Jo Maugham QC and uses the law to deliver a better society.
5. The crowdfunding page can be seen here https://www.crowdjustice.com/case/secretbrexitstudies.