but unless the diaries are in the public domain, isn't this pretty cut and dry? If the diaries are in private hands, they're in private hands and you need permission to use their contents.
AFAIK, legally it is pretty cut and dry.
The question is:
Should it be or should there be changes in the legislation? And if you change legislation, where do you draw the line?
Because there is currently a LOT of material that might be interesting for researchers, but is only accessible if you pay a fee. As in, most material controlled by scientific publishers such as Elsevier.
With fees of some 10 dollars per article, buying access to one or two articles is affordable enough, but if you want to review some dozen to get an overview of your field of research it becomes expensive. Depending on your budget, perhaps prohibitively expensive.
The current case is no different:
The estate of Joseph Goebbels does not want to forbid the use of the diaries but they want royalties for the extracts. So there is some financial obstacle to research.
Personally, I'm in favor for easier access to scientific materials if they were created with public funds. Perhaps by putting a clause in the work contract of the researchers that they give their employers shared publishing rights.
In case of some old Nazi diaries though, I'd prefer the simple approach of waiting another 8 1/2 months. After 2015, almost all of those will be in the public domain anyway :-)