In 1996, Professor Elizabeth Warren made a proposal to the American Law Institute and the Drafting Committee for Article 9 for a “20 percent set aside” for unsecured claimants. As I understand it, her proposal would amend Section 9-301 of Article 9 (the section that now implicitly subordinates a lien creditor to a prior perfected secured creditor).
White, James J. "The Slippery Slope to Bankruptcy - Should Some Claimants Get a 'Carve-Out' from Secured Credit? No: It's a Populist Craving for a Petit Bourgeois Valhalla." Bus. L. Today 7, no. 3 (1998): 33, 37-9.