Mont. Code Ann. § 39-2-705

Any contract or agreement entered into by any person, company, or corporation with its servants or employees whereby such person, company, or corporation shall be released or discharged from liability or responsibility on account of personal injuries received by such servants or employees while in the service of such person, company, or corporation, by reason of the negligence of such person, company, or corporation, or the agents or employees thereof, shall be absolutely null and void.