QUESTIONS CERTIFIED
Pursuant to Rule 23 of the Rules of the Supreme Court of Tennessee, 1 this Court has accepted two questions certified to us by the United States District Court for the Eastern District of Tennessee. The questions are as follows:
1. Whether products liability defendants in a suit for personal injuries based on allegations of negligence and strict liability in tort may introduce evidence at trial that the plaintiffs employer’s alteration, change, improper maintenance, or abnormal use of the defendants’ product proximately caused or contributed to the plaintiff’s injuries.
2. If “no,” of what effect is Tenn.Code Ann. § 29-28-108?
As explained below, the answer to the first certified question is that products liability defendants in a suit for personal injuries based on allegations of negligence and strict liability in tort may introduce relevant evidence at trial that the plaintiff’s employer’s alteration, change, improper maintenance, or abnormal use of the defendants’ product was a cause in fact of the plaintiff’s injuries. The jury may consider all evidence relevant to the actions of the employer with respect to the defendants’ product in assessing whether the plaintiff has met his burden of establishing the elements necessary to recover against the defendants. However, in making that determination, the jury may not assess fault against the employer. Our answer to the first question makes it unnecessary to reach the second one.
FACTS AND PROCEDURAL BACKGROUND
In this products liability action, the plaintiff, William Snyder, was employed by Sara Lee Knit Products as a technician at its plant in Mountain City. Sara Lee used presses in its plant to compress cotton into bales. These presses, called “cotton balers,” collected cotton in the top portion of the machine, which then vertically compressed the cotton into the lower half of the machine. A ram would then move horizontally forward to press the cotton into a bale.
On February 1, 1992, the plaintiff was working on a cotton baler in his employer’s plant that had stopped in mid-cycle. Without first disconnecting power to the baler, the plaintiff stuck his arm into the machine to remove loose cotton covering a protective switch. The plaintiffs arm was inserted into the machine through an opening where a metal panel or barrier would have normally been bolted. While the plaintiff’s arm was inside the machine, the machine engaged, causing injury to the plaintiff’s arm. According to the plaintiff, he had not removed the metal panel and did not know who had. However, he admits to removing and replacing it on previous occasions.
On December 3, 1992, the plaintiff filed a products liability suit against LTG Lufttech-nische GmbH, a German corporation, and LTG Technologies, Inc., a South Carolina corporation. Plaintiff alleged that these defendants were the manufacturers and sellers of the baler that injured him. In turn, these defendants named HSM Pressen GmbH, a German corporation, as a party, claiming that it was the manufacturer of the baler at issue. The Travelers Insurance Company intervened to assert its subrogation claim for the amount paid to the plaintiff as the work *254 ers’ compensation carrier for the plaintiffs employer, Sara Lee. 2
The plaintiffs suit seeks recovery for personal injury based upon strict liability in tort, negligence and breach of warranty. Plaintiff claims that the defendants negligently designed and manufactured the baler, negligently failed to warn of the machine’s dangers, and are liable for breach of warranties.
In response, the defendants insist that the cotton baler in question was state of the art and that it was neither defective nor unreasonably dangerous when it left their control. 3 They also claim that the machine was not defectively designed. Rather, the defendants assert that the plaintiffs employer altered or failed to maintain the machine by removing the bolted metal panel through which the plaintiff stuck his arm, thereby constituting a subsequent intervening act of negligence that caused the plaintiffs injuries. Thus, according to the defendants, it was the plaintiffs employer’s conduct that rendered the baler defective or unreasonably dangerous. See Tenn.Code Ann. § 29-28-108 (“If a product is not unreasonably dangerous at the time it leaves the control of the manufacturer or seller but was made unreasonably dangerous by subsequent unforeseeable alteration, change, improper maintenance or abnormal use, the manufacturer or seller is not liable.”). The defendants further maintain that removing the protective panel from the machine and attempting maintenance and repairs without first disconnecting the power violated safety provisions of the machine’s operating and maintenance instructions.
An order certifying to this Court the two questions set forth above was issued by the United States District Court for the Eastern District of Tennessee at Greenville. The district judge opined that this Court’s decision in
Ridings v. Ralph M. Parsons Co.,
ANALYSIS
In
McIntyre v. Balentine,
Four years after
McIntyre
was decided, the case of
Ridings v. Ralph M. Parsons Co.,
The defendants in
Ridings
argued that fault could be apportioned to the plaintiffs employer and that their liability could be decreased accordingly, without the imposition of legal liability upon the employer.
Id.
at 81. The defendants also claimed that excluding the plaintiffs employer from those persons to whom fault could be attributed violated the principle stated in
McIntyre
that a party be held hable only for the percentage of the plaintiffs damages caused by that party.
See McIntyre,
This Court rejected the defendants’ position in
Ridings,
stating that it was “not consistent with the Tennessee doctrine of comparative fault.”
Ridings,
In the present case, the defendants maintain that Ridings was wrongly decided and should be reversed. They claim that Rid-ings is not consistent with McIntyre’s objective of fairness because they will have to bear whatever percentage of fault the jury would have accessed against the plaintiff’s employer. We carefully considered and rejected this same argument in Ridings, stating that
[t]he rationale of McIntyre postulates that fault may be attributed only to the persons against whom the plaintiff has a cause of action in tort_ Since the plaintiffs employer cannot be made a party to the plaintiffs tort action for personal injuries sustained in the course and scope of his employment, the rationale of McIntyre, both as to principle and procedure, will not *256 permit fault to be attributed to the plaintiffs employer.
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Limiting the parties to whom fault may be attributed to those subject to liability, accomplishes the policy objective of fairness and efficiency.
Ridings,
There is no question that the Court in Ridings considered the “fairness” arguments advanced here by the defendants and made a policy decision to leave immune employers out of the assessment of fault. We thus decline the defendants’ invitation to reverse Ridings or otherwise depart from the rule adopted in that decision.
However, before leaving Ridings, we are inclined to add that our decision in that case can best be understood when considered in the analytical context in which the case came to the Court. The defendants in Ridings, like the defendants here, wanted the jury to assess fault against the employer by arguing that the employer’s actions were the proximate, or legal, cause of the plaintiffs injuries. Of course, the employer cannot be found to be the proximate, or legal, cause of the plaintiffs injuries because the employer is immune from tort liability under Tenn.Code Ann. § 50-6-108(a). By enacting Tenn.Code Ann. § 50-6-108(a), the legislature has already determined that for policy reasons the employer may not be the legal cause of the plaintiffs injuries.
This is not to say, however, that the employer cannot be found by the trier of fact to have been a cause in fact of the plaintiffs injuries. 6 If the rule were otherwise, the defendants would effectively be precluded from presenting a defense. A defense that the product was not defective or unreasonably dangerous when it left the defendants’ control would not be credible unless the defendants were permitted to introduce evidence as to what actually happened to the product leading up to the incident that injured the plaintiff. Excising the employer from that discussion would be tantamount to drawing a line which would make discussion of the case to be tried difficult, if not impossible. 7 The end result would be that the jury would not hear evidence of the true facts surrounding the product that caused the plaintiffs injuries but, nonetheless, be asked to determine fault and hence liability for damages. Prohibiting the introduction of such evidence could result in a defendant, who was not a cause in fact of the plaintiffs injuries, being required to pay for the harm anyway.
CONCLUSION
In light of the foregoing discussion, our answer to the first certified question is that products liability defendants in a suit *257 for personal injuries based on allegations of negligence and strict liability in tort may introduce relevant evidence at trial that the plaintiffs employer’s alteration, change, improper maintenance, or abnormal use of the defendant’s product was a cause in fact of the plaintiffs injuries. Put another way, the jury may consider all evidence relevant to the event leading up to the incident that injured the plaintiff. The defendants may not, however, ask the jury to assign fault to the employer. That is, the defendants may not take the legal position that the employer’s actions were the legal cause of the plaintiffs injuries. The jury should be instructed that it may consider the actions of the employer only in assessing whether the plaintiff has met his burden of establishing the elements necessary to recover against the defendants. Also, the jury should be instructed that it may not, in making that determination, assess fault against the employer. Finally, the trial judge should give an instruction that lets the jury know that the employer’s legal responsibility will be determined at a later time or has already been determined in another forum.
The clerk will transmit this opinion in accordance with Rule 23, Section 8 of the Rules of the Supreme Court. The costs in this Court will be taxed to the defendants.
Notes
. "The Supreme Court may, at its discretion, answer questions of law certified to it by the Supreme Court of the United States, a Court of Appeals of the United States, a District Court of the United States in Tennessee, or a United States Bankruptcy Court in Tennessee. This rule may be invoked when the certifying court determines that, in a proceeding before it, there are questions of law of this state which will be determinative of the cause and as to which it appears to the certifying court there is no controlling precedent in the decisions of the Supreme Court of Tennessee." Sup.Ct. R. 23, Sec. 1.
. The extent, if any, to which an employer’s subrogation interest in recovering workers’ compensation benefits paid to an injured employee who brings a tort claim against a third party is affected by Tennessee’s adoption of comparative fault will be dealt with in our forthcoming opinion in
Castleman v. Ross Engineering Inc.,
- S.W.2d-,
. Tenn.Code Ann. § 29-28-105 provides that a "manufacturer or seller of a product shall not be liable for any injury to person or property caused by the product unless the product is determined to be in a defective condition or unreasonably dangerous at the time it left the control of the manufacturer or seller. In making this determination, the state of scientific and technological knowledge available to the manufacturer or seller at the time the product was placed on the market ... is applicable." Tenn.Code Ann. § 29-28-105(a), (b).
.Employers are immune from tort liability due to the exclusive remedy provision of the workers’ compensation law. Tenn.Code Ann. § 50-6-108(a).
. In
McIntyre,
we stated that "defendants called upon to answer allegations [of] negligence be permitted to allege, as an affirmative defense, that a non-party caused or contributed to the injury or damage for which recovery is sought. In cases where such a defense is raised, the trial court shall instruct the jury to assign this non-party the percentage of the total negligence for which he is responsible.”
McIntyre,
. The distinction between cause in fact and proximate, or legal, cause is not merely an exercise in semantics. The terms are not interchangeable. Although both cause in fact and proximate, or legal, cause are elements of negligence that the plaintiff must prove, they are very different concepts.
Ridings,
. For example, in the present case, the defendants would be restricted from presenting evidence that the plaintiff’s employer altered, changed, or improperly maintained the cotton bailer that injured the plaintiff by removing the metal panel that covered the area into which the plaintiff stuck his arm.
