In any action brought against any such common carrier under or by virtue of any of the provisions of this article, to recover damages for injury to, or the death of, any of its employees, the question as to whether the negligence or violation of law claimed to have caused or contributed to the injury or death of such employee did in substance cause or contribute to such injury or death, and the question as to whether such negligence or violation of law was the proximate cause of such injury or death shall, in all cases, be for the determination of the jury.
C.R.S. § 40-33-104