43 CFR § 3836.21
How do I qualify for a deferment of assessment work on my mining claims?
June 11, 2020
You qualify for a deferment of assessment work if—
(a) You have a mining claim or group of mining claims that you cannot enter or gain access to because—
(1) The claims are surrounded by lands owned by others, including BLM, and the land owner has refused to give you a right-of-way or you are in litigation regarding the right-of-way or in the process of acquiring the right-of-way under state law; or
(2) Some other legal impediment prevents your access.
(b) You have received a declaration of taking or notice of intent by the Federal Government to take the claim.