Mont. Code Ann. § 39-71-407

(1) Each For workers' compensation injuries, each insurer is liable for the payment of compensation, in the manner and to the extent provided in this section, to an employee of an employer that it insures who receives an injury arising out of covered under plan No. 1, plan No. 2, and in the course of employment or, in the case of death from the injury, to the employee's state fund under plan No. 3 that it insures who receives an injury arising out beneficiaries, if any. of and in the course of employment or, in the case of death from the injury, to the employee's beneficiaries, if any.

(10) An employee is not eligible for benefits payable under this chapter unless the entitlement to benefits is established by objective medical findings that contain sufficient factual and historical information concerning the relationship of the worker's condition to the original injury.

(11) For occupational diseases, every employer enrolled under plan No. 1, every insurer under plan No. 2, or the state fund under plan No. 3 is liable for the payment of compensation, in the manner and to the extent provided in this chapter, to an employee of an employer covered under plan No. 1, plan No. 2, or the state fund under plan No. 3 if the employee is diagnosed with a compensable occupational disease.

(11) (a) For occupational diseases, every employer enrolled under plan No. 1, every insurer under plan No. 2, or the state fund under plan No. 3 is liable for the payment of compensation, in the manner and to the extent provided in this chapter, to an employee of an employer covered under plan No. 1, plan No. 2, or the state fund under plan No. 3 if the employee is diagnosed with a compensable occupational disease.

(b) The provisions of subsection (11)(a) apply to presumptive occupational disease if the employee is diagnosed and meets the conditions of 39-71-1401 and 39-71-1402.

(12) An insurer is liable for an occupational disease only if the occupational disease:

(a) is established by objective medical findings; and

(b) arises out of or is contracted in the course and scope of employment. An occupational disease is considered to arise out of or be contracted in the course and scope of employment if the events occurring on more than a single day or work shift are the major contributing cause of the occupational disease in relation to other factors contributing to the occupational disease.

(13) When compensation is payable for an occupational disease, the only employer liable is the employer in whose employment the employee was last injuriously exposed to the hazard of the disease.

(14) When there is more than one insurer and only one employer at the time that the employee was injuriously exposed to the hazard of the disease, the liability rests with the insurer providing coverage at the earlier of:

(a) the time that the occupational disease was first diagnosed by a health care provider; or

(b) the time that the employee knew or should have known that the condition was the result of an occupational disease.

(15) In the case of pneumoconiosis, any coal mine operator who has acquired a mine in the state or substantially all of the assets of a mine from a person who was an operator of the mine on or after December 30, 1969, is liable for and shall secure the payment of all benefits that would have been payable by that person with respect to miners previously employed in the mine if acquisition had not occurred and that person had continued to operate the mine, and the prior operator of the mine is not relieved of any liability under this section.

(16) As used in this section, "major contributing cause" means a cause that is the leading cause contributing to the result when compared to all other contributing causes.

(2) An injury does not arise out of and in the course of employment when the employee is:

(2) (a) An insurer on a paid or unpaid break, is liable for an injury, as defined in 39-71-119, if not at a worksite of the injury employer, is and established by objective medical findings and if the is claimant establishes that it is more probable than not that:

(i) a claimed injury has occurred; or

(ii) a claimed injury aggravated a preexisting condition.

(b) Proof that it was medically possible that a claimed injury occurred engaged in an unpaid social or that recreational activity, regardless of whether the claimed injury aggravated a preexisting condition is not sufficient to establish liability. employer pays for any portion of the activity or whether the activity occurs at the worksite of the employer. The exclusion from coverage of this subsection (2)(b) does not apply to an employee who, at the time of injury, is on paid time while participating in a social or recreational activity and whose presence at the activity is required or requested by the employer. For the purposes of this subsection (2)(b):

(i) "requested" means the employer asked the employee to assume duties for the activity so that the employee's presence is not completely voluntary and optional and the injury occurred in the performance of those duties; and

(ii) "social or recreational activity" means an activity that is generally undertaken by individuals for exercise, relaxation, pleasure, or voluntary or optional preparation related to the employment.

(3) An employee who suffers an injury or dies while traveling is not covered by this chapter unless:

(3) (a) An insurer is liable for an injury, as defined in 39-71-119, only if the injury is established by objective medical findings and if the claimant establishes that it is more probable than not that:

(a) (i) the employer furnishes the transportation a claimed injury has occurred; or the employee receives reimbursement from the employer for costs of travel, gas, oil, or lodging as a part of the employee's benefits or employment agreement; and

(ii) the travel is necessitated by a claimed injury has occurred and on behalf of the employer as an integral part or condition of the employment; or aggravated a preexisting condition.

(b) the travel is required by the employer as part of the employee's job duties. Proof that it was medically possible that a claimed injury occurred or that the claimed injury aggravated a preexisting condition is not sufficient to establish liability.

(c) Objective medical findings are sufficient for a presumptive occupational disease as defined in 39-71-1401 but may be overcome by a preponderance of the evidence.

(4) An employee is not eligible for benefits otherwise payable under this chapter if the employee's use of alcohol or drugs not prescribed by a physician is the major contributing cause of the accident. However, if the employer had knowledge of and failed to attempt to stop the employee's use of alcohol or drugs, this subsection does not apply.

(4) (a) An employee who suffers an injury or dies while traveling is not covered by this chapter unless:

(i) the employer furnishes the transportation or the employee receives reimbursement from the employer for costs of travel, gas, oil, or lodging as a part of the employee's benefits or employment agreement and the travel is necessitated by and on behalf of the employer as an integral part or condition of the employment; or

(ii) the travel is required by the employer as part of the employee's job duties.

(b) A payment made to an employee under a collective bargaining agreement, personnel policy manual, or employee handbook or any other document provided to the employee that is not wages but is designated as an incentive to work at a particular job site is not a reimbursement for the costs of travel, gas, oil, or lodging, and the employee is not covered under this chapter while traveling.

(c) As provided in this subsection (4), whether the employer furnishes the transportation or the employee receives reimbursement for costs of travel, gas, oil, or lodging is not dispositive of whether the employee is covered by this chapter.

(5) If a claimant who has reached maximum healing suffers a subsequent nonwork-related injury to the same part of the body, the workers' compensation insurer is not liable for any compensation or medical benefits caused by the subsequent nonwork-related injury.

(5) (a) Except as provided in subsection (6), an employee is not eligible for benefits otherwise payable under this chapter if the employee's use of alcohol or drugs not prescribed by a physician is the major contributing cause of the accident.

(b) For the purposes of this subsection (5), if an employee fails or refuses to take a drug test after the accident and if the testing procedures comply with federal drug testing statutes and administrative regulations applicable to private sector employers and employees as provided in Title 39, chapter 2, there is a presumption that the major contributing cause of the accident was the employee's use of drugs not prescribed by a physician.

(6) An employee is not eligible for benefits payable under this chapter unless the entitlement to benefits is established by objective medical findings that contain sufficient factual and historical information concerning the relationship of the worker's condition to the original injury.

(6) (a) An employee who has received written certification, as defined in 16-12-502, from a physician for the use of marijuana for a debilitating medical condition and who is otherwise eligible for benefits payable under this chapter is subject to the limitations of subsections (6)(b) through (6)(d).

(b) An employee is not eligible for benefits otherwise payable under this chapter if the employee's use of marijuana for a debilitating medical condition, as defined in 16-12-102, is the major contributing cause of the injury or occupational disease.

(c) Nothing in this chapter may be construed to require an insurer to reimburse any person for costs associated with the use of marijuana for a debilitating medical condition, as defined in 16-12-102.

(d) In an accepted liability claim, the benefits payable under this chapter may not be increased or enhanced due to a worker's use of marijuana for a debilitating medical condition, as defined in 16-12-102. An insurer remains liable for those benefits that the worker would qualify for absent the worker's use of marijuana for a debilitating medical condition.

(7) As used in this section, "major contributing cause" means a cause that is The provisions of subsection (5) do not apply if the leading cause contributing employer had knowledge of and failed to attempt the to result when compared to all other contributing causes. stop the employee's use of alcohol or drugs not prescribed by a physician. This subsection (7) does not apply to the use of marijuana for a debilitating medical condition because marijuana is not a prescribed drug.

(8) If there is no dispute that an insurer is liable for an injury but there is a liability dispute between two or more insurers, the insurer for the most recently filed claim shall pay benefits until that insurer proves that another insurer is responsible for paying benefits or until another insurer agrees to pay benefits. If it is later proven that the insurer for the most recently filed claim is not responsible for paying benefits, that insurer must receive reimbursement for benefits paid to the claimant from the insurer proven to be responsible.

(9) If a claimant who has reached maximum healing suffers a subsequent nonwork-related injury to the same part of the body, the workers' compensation insurer is not liable for any compensation or medical benefits caused by the subsequent nonwork-related injury.

Liability of insurers -- – limitations

Void on occurrence of contingency--sec. 7, Ch. 158, L. 2019.

Temporary

Liability of insurers – limitations

Effective on occurrence of contingency