When it comes to legal organizations or pro bono attorneys in Montana. The only rule of relevance is Article I, Section 3(g) of the State Bar of Montana which allows retired attorneys to practice as emeritus Montana pro bono attorneys in order to provide pro bono services to the state and people of Montana. Montana pro bono attorneys cannot engage in the actual practice of law except if it is allowed by at the Montana courts or in assistance with a non profit legal organization. For info on specific admission check out Montana's pro hac vice admissions.