From a manuscript catalogue to a research claim
A work, a surviving copy of that work and a digital image of the copy are related but distinct. The work may have circulated before the surviving volume was made. The volume may include later notes or repairs. The image records selected surfaces under particular conditions. Specify which of these your argument concerns.
The Michigan collection overview describes manuscripts across many subjects, including jurisprudence. Use the catalogue to identify a candidate, then record the shelfmark, attributed title, language and any dates or uncertainties supplied by the library. A collection-level description cannot establish the contents or date of an individual volume.