There's a few working pieces. There's significant jurisprudence starting as early as Roman times on the idea of 'law like' instruments garnering protections by virtue of their role in public regulation. The UK has a number of very plainly stated cases on the matter that are pursuasive in the US as well.

Some attempt to attenuate copyright's ability to exclude in the case of law-like works by using carve-outs in copyright, but this solution isn't scaleable - Fair dealing and Fair use are consistently under siege, attacked in international-level agreements and interpreted fairly inconsistently between jurisdictions.

Instead, my proposal is to treat law-like documents as being in the public domain but only to the extent that they are being used for their law-like purpose.

Accordingly, even if we change the nature of databased works in the future, we 1) assure the access of the public to codes, regulations, registration documents and other key elements of law, 2) ensure that the government's treating of these documents is not hampered by transmission or duplication restrictions arising out of copyright, and 3) protect stakeholder interests by restricting the scope of use to the areas where there is a public purpose to the dissemination of these works.

I can send the case names privately if you'd like.