I greatly enjoyed JJV's recent post on the application of law to The Lord of the Rings. It reminded me of an earlier article dealing with the promise made by Sauron's emissary to King Durin of the Dwarves, in which dominion over Moria was promised in exchange for Bilbo Baggins. The wrinkle in all of that, of course, was the prior presence in said property of the Balrog, which engendered a hilariously learned discussion of just how much authority Sauron had over the current resident of Khazad-dum.
The link I found does not have the entire article but JJV assures me that his post links to a link that links to a link (etc.) where one may eventually find the whole thing. Which, as they say, should be read. But only if you have made it to the end of this post. Don't say I didn't warn you.
My own take on this is that Sauron probably had the authority to evict the Balrog (unnamed but referred to in most contract law casebooks as "Flame of Udun Doe") based on his position as lieutenant of Morgoth (not terminated despite his boss' exile beyond the Wall of Night) but that only a personal visit by Sauron to Moria would have done the trick. Sauron could claim that, himself having been evicted from Dol Guldur - relatively close and convenient to Moria (no more than two bus transfers) he was unable to do so from his more remote domicile in Barad-Dur, but it is uncertain whether a jury would have returned a verdict other than "Shire! Baggins!"