delivered the Opinion of the Court.
We granted certiorari to review the court of appeals unpublished decision, Young v. Clark, No. 89CA0421 (Colo. App. Mar. 22, 1990). The issue to be resolved is whether the trial court’s submission of a “sudden emergency” instruction in this automobile collision case was improper. The court of appeals held that the trial court did not err by so instructing the jury. We affirm.
I.
This case arose from a rear-end collision on February 6, 1987, at approximately 10:30 a.m. The plaintiff, John Young (Young), and the defendant, Holly Clark (Clark), were both travelling eastbound in the center lane on Colorado Highway 36. Construction on the highway caused all traffic to slow to an estimated thirty-five to forty-five miles per hour. One unidentified driver, who was four to five cars ahead of Young, pulled out of the center lane into the right-hand lane and then swerved abruptly back into the center-lane traffic, forcing all drivers behind him to apply their brakes. At that time, Clark had looked over her shoulder while attempting to change lanes. Her passenger, Susan Baldwin, yelled to Clark upon seeing that all traffic ahead had stopped. Clark applied her brakes and swerved to the left, but was unable to avoid colliding with the rear of Young’s car.
*365Young filed suit against Clark on June 11,1987, claiming that he sustained personal injuries as a result of the accident that was caused by Clark’s negligent operation of her car. Young’s complaint was later amended to add a loss of consortium claim on behalf of Young’s wife. Clark denied that she was negligent and designated the unidentified driver as a nonparty, claiming that he was responsible for causing the accident.
The trial court submitted the issues of Clark’s negligence, John Young’s contributory negligence, and the negligence of the designated nonparty to the jury. Included in the court’s instructions to the jury was an explanation of the “sudden emergency” doctrine. The trial court submitted this instruction over the objection of the Youngs’ attorney based on its finding that the sudden emergency doctrine remained valid under Colorado law and that the instruction served both parties “because both were confronted with the same sudden emergency.”
The jury found that the Youngs’ injuries were not caused by any negligence on Clark’s part, and consequently never determined whether John Young was negligent or whether the nonparty driver was negligent. The court of appeals held that the trial court did not err by instructing the jury on the sudden emergency doctrine. We granted certiorari to determine whether the trial court’s submission of a “sudden emergency” instruction was improper, either under the circumstances of this particular case, or because the instruction should no longer be given.
II.
The sudden emergency doctrine was developed by the courts to recognize that a person confronted with sudden or unexpected circumstances calling for immediate action is not expected to exercise the judgment of one acting under normal conditions. See W.P. Keeton, D. Dobbs, R. Keeton & D. Owen, Prosser and Keeton on the Law of Torts § 33, at 196 (5th ed.1984) [hereinafter Prosser and Keeton ].
[T]he basis of the special rule is merely that the actor is left no time for adequate thought, or is reasonably so disturbed or excited that the actor cannot weigh alternative courses of action, and must make a speedy decision, based very largely upon impulse or guess. Under such conditions, the actor cannot reasonably be held to the same accuracy of judgment or conduct as one who has had full opportunity to reflect, even though it later appears that the actor made the wrong decision, one which no reasonable person could possibly have made after due deliberation.
Id, The doctrine does not, however, impose a lesser standard of care on a person caught in an emergency situation; the individual is still expected to respond to the situation as a reasonably prudent person under the circumstances. The emergency is merely a circumstance to be considered in determining whether the actor’s conduct was reasonable. Id. at 196-97. See also Restatement (Second) of Torts § 296(1) comment b (1977) (“Among the circumstances which must be taken into account is the fact that the actor is confronted with [a sudden] emergency_”). Thus, a person may be found negligent if his actions are deemed unreasonable, despite the emergency. Prosser and Keeton § 33, at 197. The sudden emergency doctrine is available in a number of emergency situations and is used by both plaintiffs and defendants to counter charges of contributory and primary negligence. It is most commonly applied in the context of claims arising from motor vehicle accidents, as in the present case.
A.
In this automobile collision case, the trial court submitted to the jury Colorado’s pattern “sudden emergency” instruction, CJI-Civ.2d 9:10, which states: “A person who, through no fault of his or her own, is placed in a sudden emergency, is not chargeable with negligence if the person exercises that degree of care which a reasonably careful person would have exercised under the same or similar circumstances.” The Youngs first contend that *366the trial court erred by giving this instruction under the circumstances of this case because, they argue, the sudden emergency confronting Clark arose from a common, and thus foreseeable, traffic problem, and because Clark’s own negligence caused the emergency situation.1
This court has approved of giving an instruction on the sudden emergency doctrine where sufficient evidence exists that a party acted in an emergency situation not caused by the party’s own negligence. See Davis v. Cline, 177 Colo. 204, 493 P.2d 362 (1972); Cudney v. Moore, 163 Colo. 30, 428 P.2d 81 (1967); Daigle v. Prather, 152 Colo. 115, 380 P.2d 670 (1963); Stewart v. Stout, 143 Colo. 70, 351 P.2d 847 (1960); Ridley v. Young, 127 Colo. 46, 253 P.2d 433 (1953). In all of these cases, it was deemed appropriate to give a sudden emergency instruction in the context of an automobile collision.
In Davis v. Cline, 177 Colo. 204, 493 P.2d 362 (1972), an accident occurred when the defendant bus driver moved into the plaintiff’s lane of traffic, forcing the plaintiff to steer sharply to the right to avoid colliding with the bus. The plaintiff subsequently struck a high curb and was thrown against the steering wheel, resulting in the aggravation of a previous back injury. This court held that the trial court committed prejudicial error by refusing to instruct the jury on the sudden emergency doctrine when there was competent evidence to justify giving the instruction. Id. at 210, 493 P.2d at 365. In so holding, the court noted that the sudden emergency doctrine “has long been recognized in Colorado as a valid principle” based on the rationale “that in an emergency there is no time for cool reflective deliberation during which alternative courses of action might be considered and explored; but rather, the situation demands [a] speedy decision based largely upon the actor’s perception of the compelling circumstances.” Id. at 207-08, 493 P.2d at 363-64. The court further viewed the doctrine “as an evidentiary guideline by which a trier of fact may properly apply the prudent [person] rule in evaluating the evidence of negligence being considered.” Id. at 209, 493 P.2d at 364. Finally, the Davis court instructed that it was for the trier of fact to determine whether an emergency existed and, if so, whether the party’s conduct was reasonable under the circumstances. Id. at 208, 493 P.2d at 364.
This court has also ruled it proper to give the sudden emergency instruction in automobile accidents involving a rear-end collision, as in the present case. In both Daigle v. Prather, 152 Colo. 115, 380 P.2d 670 (1963), and Cudney v. Moore, 163 Colo. 30, 428 P.2d 81 (1967), the evidence indicated that the defendants each experienced brake failure while attempting to stop their vehicles prior to hitting the rear-end of the plaintiffs’ cars. In Daigle, the defendant testified that the suddenness of the brake failure prevented her from using her emergency brake or from veering to the left or right, and in Cudney, the defendant testified that “everything went so fast” that he was unable to reach his emergency brake in time and did not have room enough to swerve around the plaintiff’s car. Under these circumstances, this court found that the defendants in both cases were entitled to a sudden emergency instruction. Daigle, 152 Colo, at 119, 380 P.2d at 672; Cudney, 163 Colo, at 32, 428 P.2d at 82. See also Bartlett v. Bryant, 166 Colo. 113, 115-16, 442 P.2d 425, 426-27 (1968); Tracy v. Graf, 37 Colo. App. 323, 327, 550 P.2d 886, 890 (1976), rev’d on other grounds, 194 Colo. 1, 568 P.2d 467 (1977) (“A sudden emergency instruction in a rear-end accident case is proper where, as here, there is evidence to support that theory of defense.”).
C.R.C.P. 51.1(1) states: “In instructing the jury in a civil case, the court shall use such instructions as are contained in Colorado Jury Instruction (CJI) as are applicable to the evidence and the prevailing *367law.” Moreover, “[a]n instruction should not be given to the jury unless there is evidence introduced to support that instruction.” Converse v. Zinke, 635 P.2d 882, 889 (Colo.1981). We conclude that, by using the approved pattern instruction in CJI-Civ.2d 9:10 to advise the jury on the sudden emergency doctrine, the trial court properly followed the prevailing law of this state favoring the use of this instruction when, as here, sufficient evidence of an emergency is presented.
The Youngs contend that it was improper to give the instruction because the rear-end collision was caused by Clark’s lack of attention and failure to maintain a safe distance from Young’s car. While it is true that the sudden emergency .instruction is not available where a defendant, or a plaintiff, is obviously guilty of negligence, the question of whether an emergency arose because of some negligence by Clark was not so clear. No evidence was presented to show that Clark was following too closely to Young’s car or that she was driving too fast under the circumstances. In fact, John Young testified that he never saw how close Clark’s car was to his or how fast she was driving just prior to the accident. Clark’s passenger, Susan Baldwin, testified that Clark was not following Young’s car too closely and that she was not speeding or “going faster than the regular flow of the traffic.” The factual dispute as to whether Clark was at fault for causing the accident was therefore appropriately submitted to the finder of fact. Indeed, under CJI-Civ.2d 9:10, the jury’s application of the sudden emergency doctrine is explicitly conditioned on a finding that the actor was not placed in a perilous predicament through any fault of his or her own.2
Further, it was Clark’s theory that the negligence of the unknown driver caused the accident when the driver pulled out of the center lane of traffic and then abruptly reentered the lane several cars ahead of Young, precipitating the sudden stopping of all the cars behind the driver. Young conceded that he had to brake “hard” to avoid hitting the car in front of him and that the unknown driver probably shared some fault in causing the accident between Young and Clark. In our view, the sudden and unexpected reentry of the unknown driver into the flow of traffic provided sufficient evidence to support giving the sudden emergency instruction. See Restatement (Second) of Torts § 296(1) comment a (1977) (the sudden emergency doctrine applies “where the sudden emergency is created in any way other than by the actor’s own tortious conduct, as where it is created by the unexpected operation of a natural force or by the innocent or wrongful act of a third person ”) (emphasis added). We therefore conclude that the trial court did not act improperly in instructing the jury on the sudden emergency doctrine under the circumstances of this case.
B.
The Youngs further urge this court to follow the lead of those jurisdictions that have abolished, or curtailed the use of, the sudden emergency doctrine. See Knapp v. Stanford, 392 So.2d 196 (Miss.1980) (prospectively abolished the doctrine altogether in a 5-4 decision); Simonson v. White, 220 Mont. 14, 713 P.2d 983 (1986) (banned use of sudden emergency instruction in automobile cases); DiCenzo v. Izawa, 68 Haw. 528, 723 P.2d 171 (1986) (disapproving of sudden emergency instructions). These courts generally have denounced the usefulness of the sudden emergency instruction based upon a perceived “hazard” that the doctrine tends “to elevate its principles above what is required to be proven in a negligence action,” reasoning that “[e]ven the wording of a well-drawn instruction intimates that ordinary rules of negligence do not apply to the circumstances constituting the claimed ‘sudden emergency.’ ” Knapp, 392 So.2d at 198. See also Simon-son, 713 P.2d at 989 (“The instruction adds *368nothing to the law of negligence and serves only to leave an impression in the minds of the jurors that a driver is somehow excused from the ordinary standard of care because an emergency existed.”).
Such reasoning, in our view, is based on unfounded assumptions about how jurors perceive an instruction explaining the relatively simplistic sudden emergency doctrine. The pattern instruction used by Colorado courts, CJI-Civ.2d 9:10, is a clear statement of the doctrine and obligates the finder of fact to do nothing more than apply the objective “reasonable person” standard to an actor in the specific context of an emergency situation. It thus does not operate to excuse fault but merely serves as an explanatory instruction, offered for purposes of clarification for the jury’s benefit.3
The Youngs also maintain that the sudden emergency doctrine should be abolished because its original purpose, to overcome the harsh effect of the former contributory negligence defense whereby a plaintiff’s negligence acted as a complete bar to recovery, is no longer served with the enactment of comparative negligence in this state. We find no merit in this argument, based on our conclusion that the sudden emergency doctrine is consistent with this state’s comparative negligence scheme.
Colorado's comparative negligence statute, § 13-21-111, 6A C.R.S. (1987), was enacted in 1971 “to ameliorate the harshness of the complete bar resulting from common law contributory negligence.” Montgomery Elevator Co. v. Gordon, 619 P.2d 66, 70 (Colo.1980). Under the statute, a plaintiff’s contributory negligence shall not bar recovery if such negligence was not as great as the defendant’s negligence, “but any damages allowed shall be diminished in proportion to the amount of negligence attributable to” the plaintiff. § 13-21-111(1). Hence, section 13-21-111 sets forth a method for apportioning damages in accordance with the amount of negligence attributable to each party. Consistent with this apportionment scheme, “[t]he sudden emergency instruction informs the jury ... how it is to allocate fault and apportion damages when the conduct of the person in question is that of an ‘ordinarily prudent person’ when faced with an emergency situation.” Compton v. Pletch, 561 N.E.2d 803, 807 (Ind.App. 1990). Significantly, the doctrine explains to the jury the standard of conduct expected of defendants and plaintiffs who act under the stress of an emergency situation. Finding no friction between the comparative negligence scheme of allocating fault and the sudden emergency doctrine, we conclude that abolishing the doctrine on this ground is unwarranted. Accord Compton, 561 N.E.2d at 807 (“[Ujnder either a contributory negligence or comparative fault system, the sudden emergency doctrine is a vital tool to explain to a jury the standard of conduct to determine ‘fault’ in an emergency.”). Contra Knapp v. Stanford, 392 So.2d 196, 198 (Miss.1981) (the sudden emergency doctrine confuses the principle of comparative negligence); Eslinger v. Ringsby Truck Lines, 195 Mont. 292, 302, 636 P.2d 254, 260 (1981) (“in view of this jurisdiction’s adoption of the doctrine of comparative negligence,” instruction should not be given in “ordinary automobile accident case”).
Lastly, the Youngs argue that the usefulness of the sudden emergency doctrine was abrogated with the enactment of section 13-21-111.5, 6A C.R.S. (1987), which permits the finder of fact to “consider the degree or percentage of negligence or fault of a person not a party to the action, based upon evidence thereof, which shall be admissible, in determining the degree or percentage of negligence or fault of those persons who are parties to such action.” § 13-21-111.5(3)(a). We fail to see the logic in this argument. The sudden emergency instruction provides that a person “is *369not chargeable with negligence” if the person acts as a “reasonably careful person” under the given emergency situation, not of the person’s own making. Section 13-21-111.5(3) allows for the consideration of a nonparty’s negligence or fault. Thus, the designation of the unidentified driver in the present case enabled Clark to present evidence in support of her theory that she was not at fault for creating the emergency situation. We therefore conclude that the sudden emergency doctrine is compatible with the designation of nonparties provision in section 13-21-111.5(3).
The sudden emergency doctrine is a long-established principle of law in this jurisdiction. We choose to leave the doctrine intact, and continue to uphold the propriety of giving the sudden emergency instruction where competent evidence is presented that a party was confronted with a sudden or unexpected occurrence not of the party’s own making.4 We affirm the court of appeals judgment.
LOHR, J., dissents, and ERICKSON, J., joins in the dissent.. We note that, from our review of the instructions tendered to the jury, no instruction was submitted advising that when a driver of a motor vehicle hits another vehicle in the rear the law presumes that the driver was negligent. See CJI-Civ.2d 11:12. We therefore do not address the effect such an instruction would have in the present case.
. The language of CJI-Civ.2d 9:10, "[a] person who, through no fault of his or her own, is placed in a sudden emergency” (emphasis added), calls upon the finder of fact to make the initial determination as to whether the emergency situation was created by the actor’s own tortious conduct.
. Other explanatory instructions pertaining to negligence appear in CJI-Civ.2d 9:12 and 9:13. CJI-Civ.2d 9:12 instructs: "The occurrence of an accident does not raise any presumption of negligence on the part of either the plaintiff or the defendant.” CJI-Civ.2d 9:13 advises: "To look in such a manner as to fail to see what must have been plainly visible is to look without a reasonable degree of care and is of no more effect than not to have looked at all."
. Contrary to the Youngs’ argument, we do not find Lewis v. Buckskin Joe’s, Inc., 156 Colo. 46, 396 P.2d 933 (1964), to be persuasive authority for abolishing the sudden emergency doctrine in this state. The Lewis court prospectively banned the trial courts from giving an instruction on unavoidable accident. This ruling has no bearing whatsoever on the viability of Colorado’s sudden emergency instruction. An unavoidable accident is an accident that occurs without anyone’s fault. Lewis, 156 Colo, at 62, 396 P.2d at 941. The unavoidable accident instruction was banned because it essentially told the jury to find for the defendant. A sudden emergency instruction, on the other hand, does not force a particular conclusion on the jury; rather, it merely informs the jury that an emergency is a circumstance for it to consider in ascertaining whether an actor’s conduct was reasonable.