Colorado Supreme Court Emphasizes Foreseeability in Proximate Cause Analysis


In a case that “truly tests the boundaries of the proximate cause inquiry,” the Colorado Supreme Court recently expounded on — and arguably altered — the standards governing the analysis of causation not only under the Colorado Premises Liability Act, C.R.S. section 13-21-115(3), but for all common law tort claims. 

In doing so, the court has made foreseeability a prime focus of the proximate cause inquiry under Colorado law, expanding property owners’ exposure to liability for intentional harmful acts carried out by third parties on the property and potentially expanding liability for tort defendants in other contexts where the actions of multiple parties contribute to the same harm. The case signals a limit on the “predominant cause” doctrine, which has previously allowed property owners and tort defendants to evade liability for intentional conduct of others. At the same time, the case highlights that duty-of-care remains a viable means to restrict liability for higher-level corporate entities not in a special relationship with the plaintiff.

The case, Rocky Mountain Planned Parenthood, Inc. v. Wagner, arose from a 2015 mass shooting at a Planned Parenthood facility in Colorado Springs. After observing videos released by an anti-abortion group purporting to depict Planned Parenthood staff discussing selling fetal tissue and organs for medical research, Planned Parenthood facilities throughout the country began seeing a spike in threats against the organization’s facilities and staff members. Among the anti-abortionists who observed the videos was Robert Dear. Enraged by the videos, Dear went to the Planned Parenthood facility in Colorado Springs armed with numerous guns, propane tanks and a ballistic vest. He began firing on individuals in the parking lot, then continued the massacre inside the building. Following a five-hour standoff with police, Dear surrendered. Three people were killed, and nine others were injured.

Plaintiffs — a group of injured individuals and survivors of victims — ultimately filed suit against the local Planned Parenthood chapter, Planned Parenthood of the Rocky Mountains, as well as the national parent organization, Planned Parenthood Federation of America. Plaintiffs asserted claims under the Colorado Premises Liability Act against PPRM and a negligence claim against PPFA rooted in allegations of negligent supervision and failure to require or instruct PPRM to maintain adequate safety measures. 

The trial court granted PPRM summary judgment, finding that, to the extent PPRM’s conduct may have contributed to the plaintiffs’ injuries, PPRM’s conduct was not a proximate cause of the plaintiffs’ injuries because Dear’s conduct was the “predominant” cause of the harm, and also finding that the conduct was not reasonably foreseeable. 

The trial court also granted PPFA summary judgment, holding that PPFA owed no legal duty to the plaintiffs because PPFA was not in a recognized “special relationship” with the plaintiffs that could give rise to liability based on conduct that occurred at an individual Planned Parenthood chapter’s facility. 

On appeal to the Colorado Court of Appeals, the court unanimously affirmed summary judgment for PPFA. However, with respect to PPRM, the division split, with the majority reversing summary judgment on the issue of causation. The majority held that plaintiffs produced sufficient evidence to overcome summary judgment and go to the jury on whether PPRM knew or should have known of the potential for violent acts at its facility yet failed to provide adequate security. In so ruling, the Court of Appeals diverged from prior case law recognizing that the acts of criminal mass murders constituted the “predominant” cause of injuries inflicted so as to relieve the property owner of liability as a matter of proximate cause. The court remanded the case to proceed to trial against PPRM on the CPLA claim. 

The Colorado Supreme Court granted certiorari to review two questions. First, whether an individual who acts to cause mass casualties without regard to his own survival or capture is necessarily the predominant cause of harm to the victims of his attack, such that a landowner cannot be liable under the CPLA for a failure to implement security measures that the plaintiffs allege may have prevented the harm. Second, whether the Court of Appeals erred in concluding that PPFA did not owe a duty of care to the patrons of the PPRM Colorado Springs facility. 

The Colorado Supreme Court Splits on the Issue of Proximate Cause

Affirming the judgment of the Court of Appeals, the Supreme Court split 4-3, with Justice Richard Gabriel authoring the majority opinion and Justice Melissa Hart authoring the partial dissent. 

All justices agreed on certain issues. First, and importantly, the court recognized that the CPLA incorporates common law tort principles with regard to causation under section 13-21-115(3)(c)(I). Second, the court recognized that the causation inquiry consists of two separate prongs: (1) actual — or “but for” — cause, and (2) proximate cause. The court split on precisely how the proximate cause prong of the causation analysis should operate. For the majority, Justice Gabriel emphasized the issue of foreseeability. For the three justices dissenting in part, Justice Hart emphasized the limiting principles of proximate cause, specifically focusing on the issue of whether the cause was a “substantial factor” in bringing about the harm. Both the majority and the dissent agreed that “foreseeability” and “substantial factor” played a role in assessing proximate causation. The dispute centered on which issue was dispositive. The majority and dissent also diverged on whether the court or jury ultimately should determine the proximate cause questions.

The Majority Opinion

For the majority, Justice Gabriel emphasized that the proximate (or “legal”) cause inquiry “depends largely on the question of the foreseeability of harm.” In so holding, the court reasoned that the plaintiffs had presented sufficient evidence that PPRM knew or should have known of the danger of acts of violence being carried out at its Colorado Springs facility to overcome summary judgment. The majority also stressed that the proximate cause is a question of fact for the jury to decide at trial. 

On the issue of whether Dear’s criminal conduct in carrying out the mass shooting constituted a “predominant” cause so as to relieve PPRM from liability as a matter of proximate causation, the majority held that (1) it was PPRM’s burden to prove at the summary judgment stage, (2) the standard is “difficult” to satisfy, and (3) on the record before the Court, PPRM had not satisfied its burden. The court underscored the record evidence showing that PPRM knew of risks of violence at its facilities (and even provided staff members with protective devices such as bulletproof vests), and also knew that the threat of violence increased significantly in the wake of the inflammatory videos released purporting to depict Planned Parenthood staff selling “baby body parts.” Signaling perhaps the most significant dispute with the dissent, the majority held that the jury — not the court — should be the final determiner of whether an actor is a “predominant” cause in the scenario of multiple concurrent causes involving a criminal shooter. 

Staying true to the majority’s focus on foreseeability, the court distinguished past cases finding mass acts of violence to constitute a “predominant” cause sufficient to relieve other actors of liability (including cases arising from the Columbine High School massacre and the Aurora theater shooting). The majority reasoned that the attack on PPRM — a highly controversial operation that received increased threats of violence in the days leading up to the incident — was reasonably foreseeable, whereas in these other prior cases, the attacks were not. In so holding, the Court perhaps laid a precedent expanding exposure for more “controversial” causes that receive more threats of violence than other less-political organizations. Anticipating that criticism, the majority emphasized the procedural posture of the decision (summary judgment) and forecasted that simply because it found that summary judgment was not warranted did not mean that the jury could or should ultimately find against PPRM on the proximate and predominant cause inquiries.

The Partial Dissent

By contrast, Justice Hart, joined by Justices Monica Márquez and Brian Boatright, stressed that the “substantial factor” analysis should be dispositive in cases involving mass shootings, regardless of the foreseeability of potential incidents. In addressing this issue as a matter of general tort law, Justice Hart emphasized the role of the proximate causation inquiry in counterbalancing the “virtually unlimited liability” imposed by the factual (but-for) cause prong of the causation analysis. In her view, proximate cause calls for a “policy judgment and common sense: Given the circumstances, is it fair to hold the defendant responsible for his or her conduct?” In the situation where multiple concurrent actions combine to cause a given harm, Hart reasoned that this inquiry should cut off liability as a matter of principle where at least part of the defendant’s conduct is, comparatively to other actors, much more predominant (substantial) in bringing about the harm. In the case of a mass shooting, Hart opined that the conduct of the shooter should be considered so predominant that it should categorically cut off liability for other concurrent actors such as PPRM. And significantly, Hart emphasized — in contrast to the majority — that although it can often be a jury question, the determination of whether such cause is “predominant” may also be resolved as a matter of law by the court. 

Seizing on the majority’s foreseeability analysis, the dissent forewarned of an atmosphere where controversial organizations may be exposed to increased liability, even for senseless acts of violence by criminal mass murderers. After noting the majority’s insistence that its conclusion “does not turn on whether a mass shooter’s attack is on a politically controversial business,” Hart expressed “fear that the consequence of the court’s approach is that certain businesses and activities will face entirely different risks of liability than others will.” The dissenting justices warned that if an organization is “more threat-prone” (citing not only abortion clinics, but also synagogues and Black churches), these organizations “may be found liable for their failure to mitigate or prevent mass shootings.” All of this “ignor[ing] the reality that the overwhelming—the predominant—cause of harm to victims of mass shootings is the maniacal determination of the shooter himself.” 

Unanimous Decision Affirming Summary Judgment for PPFA on Lack of Duty

The secondary issue on which all justices agreed is that PPFA did not owe a duty of care to the plaintiffs as PPRM’s invitees. Plaintiffs’ allegations against PPFA were those of nonfeasance, stemming from the alleged failure to ensure PPRM followed the national organization’s purported security mandates. As such, the plaintiffs were required to show PPFA was in a recognized “special relationship” with the plaintiffs. The Court held the plaintiffs had failed to satisfy that showing. Nor did the plaintiffs present sufficient evidence to suggest PPFA controlled the daily actions of PPRM under an alter ego theory. Based on the lack of evidence showing any control over PPRM’s day-to-day activities, the Court distinguished this case from Grenier v. Commissioner of Transportation, and Brown v. Delta Tau Delta. Instead, the court found the facts to be more analogous to University of Denver v. Whitlock, where the court concluded the connection to, and control over, the affiliate organization were too attenuated such that the university was not liable for actions of the fraternity. Likewise, the court held the plaintiffs failed to present evidence that PPFA assumed any duty to provide security and did not show either that PPFA failed to exercise reasonable care in that alleged undertaking or that plaintiffs relied on PPFA to provide the promised security at PPRM.


The Colorado Supreme Court’s holding will reach well beyond premises liability because the Court analyzed and applied common law causation principles. The opinion will likely have three main implications for tort defendants in Colorado. 

First, the primary impact is that the majority has concluded that a jury should, in most circumstances, be allowed to decide proximate cause issues, including whether one party’s actions constitute a proximate cause so as to cut off liability for other actors. In sharp contrast, the dissent would allow a more defense-friendly approach of allowing the court to decide the proximate cause issue as a matter of law, short of submission to a jury. 

Second, businesses and organizations operating in Colorado can expect increased exposure to tort liability based on known dangers and threats of violence, especially if the business operates in controversial subject matters. The majority’s emphasis on foreseeability rather than substantial-factor in its proximate cause analysis is a shift in Colorado tort law, and businesses and organizations should be cognizant of what actions they should take to protect themselves from liability based on threats or hazards known to their particular organization. For all intents and purposes, businesses that become aware of threats of violence, especially those involved in controversial causes, will have less likelihood of success of resolving claims through dispositive motions based on causation questions. 

Third, practically speaking, the predominant cause doctrine has been significantly limited. If an armed gunman intent on inflicting mass casualties against institutions with which he or she has profound philosophical differences is not always considered a predominant cause as a matter of law, then it is highly unlikely that courts will limit liability for defendants in other contexts under the predominant cause doctrine in the future. 

While narrowing defendants’ ability to resolve their liability short of trial, ultimately the precise impact of this decision will come down to the jury. Colorado juries may well agree based on the circumstances of each case that the actions of the criminal actor are predominant, thus relieving businesses of liability for lack of proximate causation. 

Or, even if the jury finds causation satisfied, the jury may still apportion the vast majority of liability to the criminal actor under comparative fault principles. What is certain is that this decision will increase costs of businesses forced to defend sympathetic claims in lengthy trials. Inevitably, at trial plaintiffs will shift their focus to the conduct of the deep-pocket defendants and away from the criminal actor, and it will be left to businesses and property owners to show that they should not be pinned with financial responsibility for the tragic consequences of the deliberate actions of another.

— Eric Hobbs is a partner and Elizabeth Hutchinson is an associate in the Denver office of Shook Hardy & Bacon

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