If a reputable library has scanned in and made available a work is this reason ("prima facie" reason) to believe at least that the library administrators had reason to believe that the work is public domain within their copyright region of concern?
E.g. Sibley Library URResearch has by now a number of works available that were first published after 1922; when I first noticed this I queried their contact people and was (re-)informed of relevant laws/exceptions to that general rule that allowed the particular works to be PD-US; that is, they had looked into it (unlike Google and Hathitrust which, much as I will happily praise them quite a lot and their support staff even more than that, are indeed mechanical in their application of certain rules and not even apparently the right ones.) But I have found some surprises on their site that I have not yet asked Sibley about- e.g. monodies by Jean Huré whose librettists died well past 1960 (so not PD-CA) and published in 1930 or thereabouts with copyright notice attached (so apparently? not PD-US - unless they were not renewed properly, or somesuch.)
Several other libraries seem to have such- BSB quartets by Thuille in manuscript (apparently? first published by 1998- unless BSB knows that they were performed in Thuille's lifetime or thereabouts, Carolus is right that we shouldn't have them and I am -guessing- neither should BSB (Bavarian Library)??) - and a Finnish library symphonies by Melartin first published around the same time (basically all of them except no.6 which was published much earlier- though fortunately, in this case I think some to most -were- premiered in Melartin's lifetime, though I would have to check.)
An especially questionable case??? - for me anyway? - is the scanned manuscript at a Portuguese library - of Joao Bomtempo's symphony 2. Ok, so far so good I guess- I'm not even sure when that was first published- maybe 30 years ago or so which may not be a problem- I forget. But this particular scanned manuscript - that's the thing. it has indications, little marginal things, by a modern recently-deceased editor, all over it- and the library page even says as much... (at least, please don't upload to IMSLP as-is
anyone who wants to go through it page by page and see if they can remove all those marginal notes, though, ok. Worth doing, I've heard it and it's a good piece, several times recorded, most recently on Naxos.)Anyhow. That was meant to be briefer, but how did Liszt paraphrase Pascal- something like I have not the energy to be briefer. Well, not quite true, but almost- will have to edit later, I fear. Hope this is of some use- apologies, I expect it isn't.
Eric