Citing Letters You Don’t Own

I assume that the auction site is only a middleman, you'd probably have to contact the actual owner, either pre or post-auction. I think that there's also a matter of who has the rights to the contents of the letters, rather than just physical possession of them.
No idea as to how this actually works.

Taylor Harbin said:

Based on my current research (shy of consulting an intellectual property lawyer) it seems that the writer owns the contents to reproducing a letter and would have to give permission. In the event someone is deceased, their heirs or perhaps only living kin would retain the rights. However, this is just for reproducing the entire letter and doesn’t appear to apply to limited quotes or summarizing the contents, so-called Fair Use.

Will need to dig into this more carefully.

Click to expand...

Whoa -- that's NOT what fair use means or is. Fair use can only be decided by a court after the fact, to begin with. But IN GENERAL, it does not apply to things like you're describing. It GENERALLY covers things like limited types of educational use, parody and satire, or news.

There is no such thing as an acceptable length that evades copyright -- I've heard this before, that if you only use whatever, half a page, 15 lines, 15 words, it's fine. It's not. It is violating copyright, no matter the length. I've never heard it conflated with fair use, but regardless, they have nothing to do with one another and it doesn't sound like what you're doing would be determined to be fair use, though, again, only a court can determine that.

Letters like anything else are covered by copyright. You need permission from the rights holder, at the least.

Consult an IP attorney.