Mont. Code Ann. § 50-12-110

A manufacturer of an investigational drug, biological product, or device, a pharmacist, a health care facility, a health care provider, or a person or entity involved in the care of a patient using an investigational drug, biological product, or device is immune from suit for any harm done to the patient resulting from the investigational drug, biological product, or device if the manufacturer, pharmacist, health care facility, health care provider, or other person or entity is complying in good faith with the terms of this act and has exercised reasonable care.