Opinion
CHIN, J.
We granted review in this case to consider important issues concerning the liability of apartment owners and other business enterprises to persons injured on their premises by the criminal acts of others, a liability based solely on the business owners’ negligent failure to provide adequate security measures to protect those who enter their property. The difficulty in resolving these issues is enhanced by the need to balance two important and competing policy concerns: society’s interest in compensating persons injured by another’s negligent acts, and its reluctance to impose unrealistic financial burdens on property owners conducting legitimate business enterprises on their premises.
In this case, we attempt to balance these interests consistent with prior case precedent. As will appear, we conclude (contrary to the Court of Appeal below) that the trial court properly granted summary judgment to defendants based on plaintiff’s failure adequately to demonstrate that defendants’ negligence was an actual, legal cause of her injuries. Here, plaintiff alleged she was assaulted on defendants’ premises by unknown assailants after she [767]*767attempted to deliver a package to an apartment resident. Although plaintiff’s evidence raised triable issues as to whether defendants owed her a duty of care and breached that duty by failing to provide additional security guards or functioning, locked security gates, her evidence was insufficient to show, as a triable factual issue, that defendants’ asserted breach of duty actually caused her injuries. Plaintiff acknowledges that her assailants were never apprehended and their identity remains unknown to her. Accordingly, she is unable to prove they would not have succeeded in assaulting her if defendants had provided additional security precautions.
Standard of Review
Because plaintiff appeals from an order granting defendants summary judgment, we must independently examine the record to determine whether triable issues of material fact exist. (Code Civ. Proc., § 437c, subd. (c); see Guz v. Bechtel National, Inc. (2000) 24 Cal.4th 317, 334 [100 Cal.Rptr.2d 352, 8 P.3d 1089] (Guz); Sharon P. v. Arman, Ltd. (1999) 21 Cal.4th 1181, 1188 [91 Cal.Rptr.2d 35, 989 P.2d 121] (Sharon P.); Ann M. v. Pacific Plaza Shopping Center (1993) 6 Cal.4th 666, 673-674 [25 Cal.Rptr.2d 137, 863 P.2d 207] (Ann M.).) We stated in Sharon P., involving a similar negligence claim resolved on summary judgment, that “To prevail on her action in negligence, plaintiff must show that defendants owed her a legal duty, that they breached the duty, and that the breach was a proximate or legal cause of her injuries. (Ann M., supra, 6 Cal.4th at p. 673.) Since defendants obtained summary judgment in their favor, ‘we review the record de novo to determine whether [they have] conclusively negated a necessary element of the plaintiff’s case or demonstrated that under no hypothesis is there a material issue of fact that requires the process of trial.’ (Id. at pp. 613-61 A.)” (Sharon P., supra, 21 Cal.4th at p. 1188.)
We recently observed in Guz that amendments to the California summary judgment statute may have modified the foregoing traditional rule by clarifying that “a moving defendant could obtain summary judgment solely by showing after opportunity for discovery, that the opposing plaintiff had failed to present triable evidence crucial to his case [citation].” (Guz, supra, 24 Cal.4th at p. 335, fn. 7; see also id. at pp. 372-374 (conc. opn. of Chin, J.); Code Civ. Proc., § 437c, subd. (o)(2) [if defendant shows element of plaintiff’s case cannot be established, burden shifts to plaintiff to show triable issue of fact, a showing supported by “specific facts,” not mere “allegations or denials of its pleadings”]; Leslie G. v. Perry & Associates (1996) 43 Cal.App.4th 472, 482 [50 Cal.Rptr.2d 785] (Leslie G.).)
We agree that the amendments to Code of Civil Procedure section 437c have modified the rule recited in Sharon P. As stated in Scheiding v. [768]*768Dinwiddie Construction Co. (1999) 69 Cal.App.4th 64, 70 [81 Cal.Rptr.2d 360] (Scheiding), “We begin by observing that the nature of summary judgment in California has changed dramatically over the last 10 years. The shifting of the burden of producing evidence that lies at the heart of this appeal could not have occurred under the summary judgment law as it previously existed. Formerly, a moving defendant had to affirmatively negate a cause of action and could not attempt to rely on a plaintiff’s vague or otherwise insufficient responses to discovery. Prior to the amendments of section 437c, the burden of proof rested entirely on the moving party to establish a right to summary judgment by demonstrating the negative proposition that the opposing party could not prevail. [Citations.] In most cases, this was a burden impossible to bear.” (Italics added.)
Scheiding continued, pointing out that “The 1992 and 1993 amendments . . . did not change the fundamental requirement that the moving party prove its right to summary judgment, but did adopt the federal mechanism of burden shifting. The new statute expressly provided that the burden does not shift to a responding party until the moving party (in this context, as usual, a defendant or cross-defendant) has been able to ‘show’ that a cause of action has no merit ‘because an element of the claim cannot be established or there is a complete defense.’ Thus, the amended language of [Code of Civil Procedure] section 437c, like its counterpart Federal Rules of Civil Procedure, rule 56 (28 U.S.C.), now places the initial burden on the moving party, and shifts it to the opposing party upon a ‘showing’ that one or more elements of the cause of action cannot be established. [Citation.]” (Scheiding, supra, 69 Cal.App.4th at pp. 71-72, italics added; see also Union Bank v. Superior Court (1995) 31 Cal.App.4th 573, 581-592 [37 Cal.Rptr.2d 653] [legislative history of 1992 and 1993 amendments].)
Therefore, we must determine whether defendants in the present case have shown, through the evidence adduced in this case, including security records and deposition testimony, that plaintiff Saelzler has not established, and cannot reasonably expect to establish, a prima facie case of causation, a showing that would forecast the inevitability of a nonsuit in defendants’ favor. If so, then under such circumstances the trial court was well justified in awarding summary judgment to avoid a useless trial. (See Guz, supra, 24 Cal.4th at p. 374 (conc. opn. of Chin, J.).)
In performing our de novo review, we must view the evidence in a light favorable to plaintiff as the losing party (Molko v. Holy Spirit Assn. (1988) 46 Cal.3d 1092, 1107 [252 Cal.Rptr. 122, 762 P.2d 46]), liberally construing her evidentiary submission while strictly scrutinizing defendants’ own showing, and resolving any evidentiary doubts or ambiguities in plaintiff’s favor. (Marshak v. Ballesteros (1999) 72 Cal.App.4th 1514, 1517 [86 [769]*769Cal.Rptr.2d 1]; Kaplan v. LaBarbera (1997) 58 Cal.App.4th 175, 179 [67 Cal.Rptr.2d 903].) We have concluded that, even giving plaintiff the benefit of these favorable rules of construction, her submission in opposition to summary judgment lacked specific facts showing that defendants’ alleged negligence was an actual, legal cause of her injuries. In other words, defendants have shown that plaintiff has not established, and cannot reasonably expect to establish, a prima facie case of causation.
Facts
On March 15, 1996, plaintiff Marianne Saelzler was an employee of Federal Express. Defendants were owners of the Sherwood Apartments, a 28-building, 300-unit apartment complex located on a several-acre site in Bellflower. Plaintiff came to the complex in midaftemoon to deliver a package to a resident. As she entered through one of the many gated entrances to the premises, she saw two young men loitering outside a security gate that had been propped open. While walking across the grounds she saw another young man already on the premises.
Plaintiff’s attempt to deliver the package proved unsuccessful because the resident was not at home. When plaintiff returned down a walk path with the package in hand, the three men confronted her, and one of them asked, “Where do you think you’re going?” When she failed to reply, another one said, “You’re not going anywhere.” Then the three of them beat her and attempted to rape her, inflicting serious injuries. After assaulting plaintiff, her assailants fled and were never apprehended.
Plaintiff’s complaint alleged that defendants, knowing that dangerous persons frequented their premises, nonetheless failed to maintain the premises in a safe condition, failed to provide adequate security, and failed to warn others of the unsafe conditions. Defendants moved for summary judgment on the basis that plaintiff was unable to establish any substantial causal link between defendants’ omissions and plaintiff’s injury. Plaintiff offered no evidence showing the identity of her assailants, whether they were gang members, whether they trespassed on defendants’ property to assault her, or whether they were tenants of the building who were permitted to pass through the security gates. Similarly, plaintiff submitted no evidence showing that the propped-open security gate was actually broken or otherwise not functioning properly, or whether her assailants entered through the gate or themselves broke it and entered. Finally, plaintiff offered no evidence that defendants reasonably or effectively could have warned members of the public such as plaintiff of unspecified dangers from unknown assailants frequenting the area.
[770]*770As the trial court found, plaintiff presented evidence that defendants knew of frequent recurring criminal activity on the premises of their 28-building apartment complex. The community of Bellflower was itself a high-crime area, with considerable juvenile gang activity occurring both on and off defendants’ premises. Plaintiff provided police reports and security logs showing that within the year prior to her assault, defendants received 41 reports of trespass, and 45 reports of occasions in which various perimeter fences and gate doors were broken or rendered inoperable. The list of criminal activity on the premises included incidents of gunshots, robberies, and sexual harassment of women, including sexual assaults and rapes.
Defendants’ security manager acknowledged that during the year preceding the assault on plaintiff, several nighttime assaults, and actual or attempted rapes, occurred on the premises. Plaintiff produced evidence that a gang called the 706 Hustlers was reportedly “headquartered” in one of defendants’ apartment buildings, conducting drug transactions, and hitting and intimidating other people on the premises. In the year prior to the incident involving plaintiff, sheriff’s officers came to the Sherwood Apartments approximately 50 times. Much of this criminal activity was reported to defendants’ manager, either in daily incident reports from their nighttime security officers or in police reports. Some pizza parlors refused to deliver to apartments in the complex, insisting residents come to the sidewalk if they wanted delivery of pizzas ordered by phone. Defendants’ apartment manager used security personnel to escort her to her vehicle whenever she left the premises.
On the other hand, defendants’ security logs showed that they took some steps to control the situation, hiring security guards to patrol the premises at night, and making frequent and regular attempts to repair broken locks or nonfunctioning gates. The record indicates that these guards were on daily duty from approximately 5:00 p.m. to 5:00 a.m. Defendants’ manager stated that the guards’ starting times ranged from 3:00 p.m. to 5:00 p.m., to make their schedule less predictable, and that defendants occasionally, on a random basis, employed full-time 24-hour security patrols on the premises. Defendants imposed a nighttime curfew on juveniles, and posted notices threatening eviction of tenants involved with drugs or gang activities. Defendants’ security logs indicated their manager and security guards regularly checked access gates for forced entry and broken locks, broke up fights, forced aggressive tenants or trespassers to leave the area, and evicted tenants involved in criminal or gang activity.
Plaintiff observes that police officers advised both defendants’ apartment manager and the head of the security firm they employed that they should [771]*771hire daytime as well as nighttime security patrols. Plaintiff filed a lengthy declaration from a security expert, Robert Feliciano, who had reviewed the security logs and depositions and had personally visited the Sherwood Apartments complex. His qualifications included service as Director of Police and Safety for the Housing Authority of Los Angeles County, as well as advanced education in public safety and several years in law enforcement. At the time he made his declaration, he was a full-time instructor in criminal justice and police science at a community college. Feliciano expressed the opinion “that this attack, assault and battery, and attempted rape on the plaintiff would not have occurred had there been daytime security and a more concerted effort to keep the gates repaired and closed. . . . It is my opinion that the premises were a haven for gangsters and hoodlums which further encouraged criminal activity as evidence [sz'c] by the long history of criminal activity in the only one year prior to this incident.”
The trial court granted summary judgment for defendants, finding plaintiff had failed to show defendants’ breach of duty to safeguard her was a proximate cause of her assault. Based on the parties’ submissions, the court found “overwhelming evidence” of prior incidents of trespass and broken or inoperable perimeter fences or gates, and a “long list” of criminal activity on the premises, including a juvenile gang possibly “headquartered” there. But despite establishing the “high foreseeability” that violent crime would occur on the premises, and defendants’ resultant duty to provide increased security, the court found that plaintiff failed to establish a “reasonably probable causal connection” between defendants’ breach of duty and plaintiff’s injuries.
A majority of the Court of Appeal reversed, concluding that plaintiff’s showing was sufficient to raise a triable causation issue for the jury. In summary, the majority held, relying primarily on commonsense and ordinary experience, that defendants’ “complete absence of required security measures” by itself reasonably could be deemed a contributing cause of any criminal activity in the area.
The Court of Appeal majority also held that defendants’ failure to provide additional security justified shifting the burden of proof to defendants, for purposes of their summary judgment motion, to conclusively establish the absence of a causal relation between their breach of duty and the assault on plaintiff by showing this particular assault would have occurred even if reasonable security measures had been taken. Because defendants “created this situation” by their flagrant failure to provide any additional daytime security, plaintiff should be relieved of her responsibility to prove a causal link between defendants’ breach of duty and the assault which produced her injuries.
[772]*772Finally, according to the Court of Appeal majority, the testimony of plaintiff’s expert, opining that the assault on plaintiff would not have occurred but for the lack of daytime security measures, was “both admissible and credible” on the causation issue.
The Court of Appeal dissent reasoned that although security measures such as guards, lights, or gates may lessen the general probability of crime occurring on the premises, plaintiff presented no evidence that such measures would have succeeded in thwarting her assailants. The dissent observed that “Neither appellant nor anyone else knows who the attackers were; they may have lived in the complex and possessed keys to the gate. Even if the attackers were nonresidents, a functioning gate would not necessarily have kept them out. The attackers might have followed [plaintiff] or some other tenant in while the gate was open, or climbed over the gate. The complex had numerous auto and pedestrian entrances through which the attackers might have come.
“Likewise, it cannot be known whether more security guards would have prevented the attack. A 300-unit, 28-building apartment complex contains many rooms, halls, entries, garages and other spaces where a rape could take place despite extensive security patrols. Again, though one can generalize that increased security patrols probably would have lessened the incidence of crime in the complex, we can never know whether they would have prevented the attack on appellant. The security officer’s logs in evidence did show that there were regular security patrols on the premises, and despite these, the attack on [plaintiff], and other crimes as well, occurred.”
Discussion
As indicated, in this case plaintiff, injured on defendants’ premises by the criminal assault of unknown assailants, seeks to recover damages from defendants on the theory that they breached their duty of care toward her. In a recent case, we explained that to prevail in such a case, the plaintiff must show that the defendant owed her a legal duty of care, the defendant breached that duty, and the breach was a proximate or legal cause of her injury. (Sharon P., supra, 21 Cal.4th at p. 1188; accord, Ann M., supra, 6 Cal.4th at p. 673; see Rest.2d Torts, § 281.) Although plaintiff devotes a substantial portion of her brief to the issue of defendants’ duty of care, defendants do not contest, for purposes of their summary judgment motion, that they may have owed and breached a duty of care toward plaintiff. Here, we are solely concerned with the issue of causation. Was defendants’ possible breach of duty a substantial factor in causing plaintiff’s injuries?
In Sharon P., the plaintiff was criminally assaulted by unknown assailants in an underground parking garage. She sued the garage owner for failure to [773]*773provide adequate security measures for its tenants and, as here, the trial court granted summary judgment against her. Although in Sharon P. we were concerned with the question of the defendants’ duty to provide security guards and other security measures, we also spoke briefly on the separate subject of causation, observing that it was “questionable whether plaintiff’s proposed [security] measures would have been effective to protect against the type of violent assault that occurred here.” (Sharon P., supra, 21 Cal.4th at p. 1196.) We noted that the courts “have rejected claims of abstract negligence pertaining to the lighting and maintenance of property where no connection to the alleged injuries was shown. [Citations.]” (Id. at pp. 1196-1197, fn. omitted, italics added.)
In Sharon P., supra, 21 Cal.4th at page 1197, we cited with approval three Court of Appeal cases holding that, assuming the defendant owed and breached a duty of care to the plaintiff, she nonetheless cannot prevail unless she shows the breach bore a causal connection to her injury. (Nola M. v. University of Southern California (1993) 16 Cal.App.4th 421, 435-439 [20 Cal.Rptr.2d 97] (Nola M.); Constance B. v. State of California (1986) 178 Cal.App.3d 200, 211-212 [223 Cal.Rptr. 645] (Constance B.); Noble v. Los Angeles Dodgers, Inc. (1985) 168 Cal.App.3d 912, 915-918 [214 Cal.Rptr. 395] (Noble).) These cases are close on point and their analyses are instructive.
In Noble, the plaintiff was assaulted in a parking lot at Dodger Stadium and sued the stadium owner on the theory it failed to provide adequate security for its patrons. At trial, the plaintiff’s expert witness opined that the owner should have employed more security guards to patrol the area, and the jury awarded the plaintiff substantial damages. On appeal, the court reversed, holding that “abstract negligence,” without proof of a causal connection between the defendant’s breach and the plaintiff’s injury, is insufficient to sustain the award. (Noble, supra, 168 Cal.App.3d at pp. 916, 918.)
In Constance B., the plaintiff was assaulted at night in the restroom at a state highway rest area. The appellate court affirmed a grant of summary judgment in defendant state’s favor, holding that the plaintiff, who saw her attacker watching her when she entered the restroom, failed to submit evidence showing that additional lighting would have prevented the attack. (Constance B., supra, 178 Cal.App.3d at pp. 211-212.) The court observed that “If liability may be premised solely on this notion [that criminals are generally deterred by strong lighting], proprietors will become the insurers of the safety of persons on their premises, subject only to the caprice of particular juries. [Citation.]” (Id. at p. 212.)
In Ñola M., the plaintiff was raped on a college campus and sued the college on the theory it should have provided more campus security. On [774]*774appeal from a judgment in the plaintiff’s favor, the Ñola M. court reversed. The court assumed for purposes of argument that the plaintiff had submitted sufficient evidence that the defendant breached a duty of care toward her, but concluded that she failed to prove the breach was a legal cause of the assault. (Nola M., supra, 16 Cal.App.4th at pp. 427-428.) The court observed that to demonstrate actual or legal causation, the plaintiff must show that the defendant’s act or omission was a “substantial factor” in bringing about the injury. (Id. at p. 427; see Mitchell v. Gonzales (1991) 54 Cal.3d 1041, 1049, 1052-1054 [1 Cal.Rptr.2d 913, 819 P.2d 872]; Rest.2d Torts, §§ 430, 431, subd. (a).) Nola M. concluded that the plaintiff must do more than simply criticize, through the speculative testimony of supposed security “experts,” the extent and worth of the defendant’s security measures, and instead must show the injury was actually caused by the failure to provide greater measures. (Nola M., supra, 16 Cal.App.4th at p. 435.) The court observed that a different rule would “make the landowner the insurer of the absolute safety of everyone who enters the premises.” (Id. at p. 437.)
In addition to the foregoing three appellate cases cited in our Sharon P. decision, other California cases support the rule that the plaintiff must establish, by nonspeculative evidence, some actual causal link between the plaintiff’s injury and the defendant’s failure to provide adequate security measures. (See Leslie G., supra, 43 Cal.App.4th atpp. 480-488; Thai v. Stang (1989) 214 Cal.App.3d 1264, 1276 [263 CaLRptr. 202] [characterizing as “pure speculation” expert testimony that absence of added security contributed to criminal assault]; Lopez v. McDonald’s Corp. (1987) 193 Cal.App.3d 495, 515 [238 Cal.Rptr. 436] [restaurant’s failure to hire security guard not shown to have been “substantial factor” in causing injuries from gunman’s attack].)
Although each of the foregoing cases supports defendants’ position here, Leslie G. is perhaps closest on point, being an appeal following summary judgment for the defendant. There, the plaintiff alleged she was raped by an unknown assailant while in the garage of her apartment building. She sued the building owners, asserting their negligence in failing to repair a broken security gate might have allowed her assailant to enter the garage. As in the present case, the plaintiff’s security expert testified at his deposition that the apartment was located in a high-crime area, that functioning security gates were critical to ensuring tenants’ safety, and that the nonfunctioning gates allowed the assailant to enter and ultimately assault the plaintiff. The expert stated his opinion that the defendant should have hired an on-site manager to perform regular inspections and repairs of the gate and other entrances, to ensure the building’s continued safety. He also opined that the assailant had selected the garage because of its isolated, remote nature, and the opportunities to hide and escape if necessary. (Leslie G., supra, 43 Cal.App.4th at pp. 478-479.)
[775]*775In Leslie G., as here, the trial court granted the defendant summary judgment on the ground the plaintiff had failed to establish a sufficient causal connection between the defendant’s negligence and the assault. Unlike the present case, in Leslie G. the Court of Appeal affirmed summary judgment, holding that the security expert’s opinions were too speculative to furnish a causal link between the defendant’s negligence and the assault. The court also observed that “Since there is no direct evidence that the rapist entered or departed through the broken gate (or even that the broken gate was the only way he could have entered or departed), [plaintiff] cannot survive summary judgment simply because it is possible that he might have entered through the broken gate. [Citations.]” (Leslie G., supra, 43 Cal.App.4th at p. 483.)
As here, the plaintiff in Leslie G. had argued that her expert’s opinion testimony was sufficient to create a triable issue of fact regarding causation. The court disagreed, observing that expert opinion resting solely on speculation and surmise is inadequate to survive summary judgment because it fails to establish a “ ‘reasonably probable causal connection’ ” between the defendant’s negligence and the plaintiff’s injury. (Leslie G., supra, 43 Cal.App.4th at p. 487, quoting from an earlier case, italics omitted.) The court concluded that “a tenant’s negligence action against her landlord for injuries resulting from the criminal assault of a third person must be supported by evidence establishing that it was more probable than not that, but for the landlord’s negligence, the assault would not have occurred. Where, as here, there is evidence that the assault could have occurred even in the absence of the landlord’s negligence, proof of causation cannot be based on mere speculation, conjecture and inferences drawn from other inferences to reach a conclusion unsupported by any real evidence, or on an expert’s opinion based on inferences, speculation and conjecture. fl[] In this case, where there is no factual basis for the expert’s opinion or for [the plaintiff’s] general assertion of causation, the conclusion is unavoidable that summary judgment was properly granted.” (Id. at p. 488, italics added, fn. omitted.)
Leslie G. and the other cases cited above fully support the trial court’s summary judgment ruling in this case. Here, by reason of the prior criminal assaults and incidents on the premises, defendants may have owed a duty to provide a reasonable degree of security to persons entering them. For purposes of discussion, we assume defendants breached that duty by failing (1) to keep all entrance gates locked and functioning, and (2) to provide additional daytime security guards to protect persons such as plaintiff. But the evidence fails to show that either breach contributed to plaintiff’s injuries in this case. As Professors Prosser and Keeton observe, “A mere possibility of such causation is not enough; and when the matter remains one [776]*776of pure speculation or conjecture, or the probabilities are at best evenly balanced, it becomes the duty of the court to direct a verdict for the defendant.” (Prosser & Keeton, Torts (5th ed. 1984) § 41, p. 269, fns. omitted, italics added.)
Plaintiff admits she cannot prove the identity or background of her assailants. They might have been unauthorized trespassers, but they also could have been tenants of defendants’ apartment complex, who were authorized and empowered to enter the locked security gates and remain on the premises. The primary reason for having functioning security gates and guards stationed at every entrance would be to exclude unauthorized persons and trespassers from entering. But plaintiff has not shown that her assailants were indeed unauthorized to enter. Given the substantial number of incidents and disturbances involving defendants’ own tenants, and defendants’ manager’s statement that a juvenile gang was “headquartered” in one of the buildings, the assault on plaintiff could well have been made by tenants having authority to enter and remain on the premises. That being so, and despite the speculative opinion of plaintiff’s expert, she cannot show that defendants’ failure to provide increased daytime security at each entrance gate or functioning locked gates was a substantial factor in causing her injuries. (See Nola M., supra, 16 Cal.App.4th at p. 427; Mitchell v. Gonzales, supra, 54 Cal.3d at pp. 1049, 1052-1054; Rest.2d Torts, § 431, subd. (a).) Put another way, she is unable to prove it was “more probable than not” that additional security precautions would have prevented the attack. (Leslie G., supra, 43 Cal.App.4th at p. 488; see Prosser & Keeton, Torts, supra, § 41, p. 269 [plaintiff must show it more likely than not defendant’s conduct was cause in fact of the result; “mere possibility of such causation is not enough”]; Rest.2d Torts, § 433B, com. a, p. 442.)
This case differs substantially from Rosh v. Cave Imaging Systems, Inc. (1994) 26 Cal.App.4th 1225 [32 Cal.Rptr.2d 136], on which plaintiff relies. There, the plaintiff was shot and severely injured by a disgruntled former employee, Hua, who had recently been terminated from employment. The plaintiff sued the security firm that was hired specifically to protect the plaintiff and other employees from such incidents. The evidence showed that the defendant had repeatedly ignored the plaintiff’s directions to bar Hua from entering the premises. Under such circumstances, the Rosh court properly found that the defendant’s negligence was a “substantial factor” in facilitating Hua’s attack on the plaintiff. (Id. at p. 1236.) Unlike the situation in Rosh, defendants in the present case had no “advance notice that a particular assailant was on the premises.” (Id. at p. 1238.)
Plaintiff, citing her expert’s declaration, opines that her injuries could have been avoided if defendants had hired roving security guards to patrol [777]*777the entire premises during the day as well as at night. Aside from the inordinate expense of providing such security for a 28-building apartment complex, the argument is entirely speculative, as assaults and other crimes can occur despite the maintenance of the highest level of security. (See Sharon P., supra, 21 Cal.4th at p. 1196; Nola M., supra, 16 Cal.App.4th at pp. 430, 435-436; Noble, supra, 168 Cal.App.3d at p. 918 [“No one can reasonably contend that even a significant increase in police personnel will prevent all crime or any particular crime”].) As previously noted, “proof of causation cannot be based on ... an expert’s opinion based on inferences, speculation and conjecture.” (Leslie G., supra, 43 Cal.App.4th at p. 488; see Nola M., supra, 16 Cal.App.4th at p. 435.) Despite her expert’s speculation, plaintiff cannot show that roving guards would have encountered her assailants or prevented the attack. As the dissenting Court of Appeal justice in this case observed, “A 300-unit, 28-building apartment complex contains many rooms, halls, entries, garages, and other spaces where a rape could take place despite extensive security patrols.”
Finally, as Ñola M. asks, “where do we draw the line? How many guards are enough? Ten? Twenty? Two hundred? ... To characterize a landowner’s failure to deter the wanton, mindless acts of violence of a third person as the ‘cause’ of the victim’s injuries is (on these facts) to make the landowner the insurer of the absolute safety of everyone who enters the premises.” (Nola M., supra, 16 Cal.App.4th at p. 437; see also 7735 Hollywood Blvd. Venture v. Superior Court (1981) 116 Cal.App.3d 901, 905 [172 Cal.Rptr. 528].) Moreover, as the Court of Appeal dissent in the present case observed, the ultimate costs of imposing liability for failure to provide sufficient daytime security to prevent assaults would be passed on to the tenants of low-cost housing in the form of increased rents, adding to the financial burden on poor renters.
Plaintiff argues that a footnote in an earlier case supports her argument that the trial court’s findings of the foreseeability of plaintiff’s injury necessarily also establishes the element of causation. (See Isaacs v. Huntington Memorial Hospital (1985) 38 Cal.3d 112, 131, fn. 8 [211 Cal.Rptr. 356, 695 P.2d 653] [affirmative finding on foreseeability issue would establish close connection between defendant’s conduct and injury suffered].) But in the present case, the trial court’s foreseeability finding was only that, given the high-crime area and history of incidents, defendants could generally foresee that criminal assaults of some kind might occur on the premises. The court did not find that defendants’ failure to provide increased security despite the foreseeability of assaults actually caused plaintiff’s injuries. Indeed, the court specially found that plaintiff did not prove any such causal link.
The Isaacs footnote was written in the context of an assault occurring in a dark, isolated parking lot lacking security guards or proper lighting, under [778]*778circumstances in which the defendant could clearly foresee that its omissions would contribute to the very assault which occurred there. We did not intend to suggest in Isaacs that a general finding of the foreseeability of some kind of future injury or assault on the premises inevitably establishes that the defendant’s omission caused plaintiff’s own injuries. Actual causation is an entirely separate and independent element of the tort of negligence. (See Sharon P., supra, 21 Cal.4th at p. 1188; Nola M., supra, 16 Cal.App.4th at p. 428, fn. 5 [referring to Isaacs’s “rather astonishing proposition” that finding of foreseeability would include finding of causation]; Noble, supra, 168 Cal.App.3d at pp. 915-916 [noting Isaacs’s “enigmatic reference” to causation].)
Plaintiff also argues in favor of the Court of Appeal majority’s practical approach to the causation issue. As previously noted, the majority held that common sense and common experience should lead us to conclude that a defendant’s “complete absence of required security measures” is necessarily a “contributing cause of most crimes occurring on that property.” Defendants observe, of course, that the evidence fails to show any such complete absence of security, as defendants provided, among other things, nighttime roving security patrols and regular daytime inspections to repair broken gates.
More fundamentally, we hesitate to adopt a rule of common sense that seemingly would prevent summary judgment on the causation issue in every case in which the defendant failed to adopt increased security measures of some kind. Ñola M. observes that “it would be grossly unfair to permit a lay jury, after the fact, to determine in any case that security measures were ‘inadequate,’ particularly in light of the fact that the decision would always be rendered in a case where the security had, in fact, proved inadequate . . . .” (Nola M., supra, 16 Cal.App.4th at p. 429.) Similarly, in Sharon P., supra, 21 Cal.4th at page 1194, we quoted with approval a legal commentator’s observation that if we simply relied on hindsight, the mere fact that a crime has occurred could always support the conclusion that the premises were inherently dangerous.
Leslie G. and Ñola M. explain that, to demonstrate actual or legal causation, the plaintiff must show that the defendant’s act or omission was a “substantial factor” in bringing about the injury. (Leslie G., supra, 43 Cal.App.4th at p. 481; Nola M., supra, 16 Cal.App.4th at p. 427; see Mitchell v. Gonzales, supra, 54 Cal.3d at pp. 1049, 1052-1054; Rest.2d Torts, §§ 430-431.) In other words, plaintiff must show some substantial link or nexus between omission and injury. Under the Court of Appeal’s “common sense” rule, the defendants’ omission itself would constitute the missing link.
[779]*779Plaintiff overstates her case when she contends that adopting the “substantial factor” approach to the causation issue would make it virtually impossible to recover from landlords or other property owners for negligence in failing to take reasonable protective measures to safeguard others from the criminal assaults of third persons. Plaintiff asserts that a finding of causation would be justified “only if a criminal is caught, and then only if the criminal testifies what specific lack of deterrence on the property made easier his or her opportunity to commit the crime . . . .” We disagree, for we can readily hypothesize cases in which the evidence discloses an actual and substantial causal link between the criminal assault and the defendant’s negligence.
Thus, in a given case, direct or circumstantial evidence may show the assailant took advantage of the defendant’s lapse (such as a failure to keep a security gate in repair) in the course of committing his attack, and that the omission was a substantial factor in causing the injury. Eyewitnesses, security cameras, even fingerprints or recent signs of break-in or unauthorized entry, may show what likely transpired at the scene. In the present case no such evidence was presented, but the circumstances in other cases may well be different. (See Leslie G., supra, 43 Cal.App.4th at p. 488, fn. 8; Rosh v. Cave Imaging Systems, Inc., supra, 26 Cal.App.4th at p. 1238 [defendant failed to act despite actual notice that particular dangerous assailant was on the premises]; Nola M., supra, 16 Cal.App.4th at pp. 436-437.)
Ñola M. lucidly explained that “We think it comes down to this; When an injury can be prevented by a lock or a fence or a chain across a driveway or some other physical device, a landowner’s failure to erect an appropriate barrier can be the legal cause of an injury inflicted by the negligent or criminal act of a third person. [Citations.] But where, as here, we are presented with an open area which could be fully protected, if at all, only by a Berlin Wall, we do not believe a landowner is the cause of a physical assault it could not reasonably have prevented. (Noble v. Los Angeles Dodgers, Inc., supra, 168 Cal.App.3d at p. 918 [‘No one can reasonably contend that even a significant increase in police personnel will prevent all crime or any particular crime’].)” (Nola M., supra, 16 Cal.App.4th at pp. 436-437.) Or as Leslie G. succinctly observed, if the plaintiff in that case could have proved her rape could have been prevented by a working security gate, “we wouldn’t be having this discussion.” (Leslie G., supra, 43 Cal.App.4th at p. 485, fn. 5.)
Plaintiff also urges us to adopt the Court of Appeal’s novel approach of shifting the proof burden on the causation issue to defendants. As previously noted, the Court of Appeal majority held that defendants’ flagrant failure to provide daytime security justified shifting the burden of proof to defendants [780]*780to conclusively establish the absence of a causal relation between its breach of duty and the assault on plaintiff; by showing this particular assault would have occurred even if reasonable security measures had been taken.
We think such a drastic shifting of the proof burden is unjustified by either the evidence in this case or prior statutory and case law. First, and contrary to the Court of Appeal’s hyperbole, the evidence discloses no flagrant failure in this case. As we have seen, most of the assaults and similar incidents of crime plaintiff has cited occurred during the night, and the record indicates defendants did provide extensive nighttime security. Moreover, plaintiff’s own evidence showed that defendants at least attempted to keep all security gates in working order, performing regular inspections and repairs.
But again, even assuming a triable issue existed regarding the extent or reasonableness of defendants’ security efforts, even a flagrant failure to provide such measures would not justify shifting to defendants the burden of conclusively proving the absence of causation. No matter how inexcusable a defendant’s act or omission might appear, the plaintiff must nonetheless show the act or omission caused, or substantially contributed to, her injury. Otherwise, defendants might be held liable for conduct which actually caused no harm, contrary to the recognized policy against making landowners the insurer of the absolute safety of anyone entering their premises. (See Sharon P., supra, 21 Cal.4th at p. 1195; Ann M., supra, 6 Cal.4th at p. 679; Nola M., supra, 16 Cal.App.4th at p. 437.)
Indeed, the Court of Appeal’s burden-shifting approach seems directly contrary to the state’s summary judgment statute, which provides that a defendant meets its burden of showing that a cause of action has no merit “if that party has shown that one or more elements of the cause of action . . . cannot be established . . . .” Once the defendant meets the foregoing burden, “the burden shifts to the plaintiff ... to show that a triable issue of one or more material facts exists as to that cause of action . . . [and] set forth the specific facts showing that a triable issue of material fact exists as to that cause of action . . . .” (Code Civ. Proc., § 437c, subd. (d)(2).) As stated in Leslie G., supra, 43 Cal.App.4th at page 482, “Under the current version of the summary judgment statute, a moving defendant need not support his motion with affirmative evidence negating an essential element of the responding party’s case. Instead, the moving defendant may . . . point to the absence of evidence to support the plaintiff’s case. When that is done, the burden shifts to the plaintiff to present evidence showing there is a triable issue of material fact. If the plaintiff is unable to meet her burden of proof regarding an essential element of her case, all other facts are [781]*781rendered immaterial. [Citations.]” (See also Rutherford v. Owens-Illinois, Inc. (1997) 16 Cal.4th 953, 968-969 [67 Cal.Rptr.2d 16, 941 P.2d 1203].)
In short, plaintiff cannot prove that defendants’ omissions were a substantial factor in causing her injuries, and no proper basis exists for shifting the burden of proof on that issue to defendants. Plaintiff has had ample opportunity, through pretrial discovery, to marshal evidence showing that defendants’ asserted breach of duty actually caused her injuries. The evidence at hand, however, merely shows the speculative possibility that additional daytime security guards and/or functioning security gates might have prevented the assault. Plaintiff’s evidence is no less speculative because she offered a security expert’s testimony. Because he was equally unaware of the assailants’ identities, his opinion regarding causation is simply too tenuous to create a triable issue whether the absence of security guards or functioning gates was a substantial factor in plaintiff’s assault.
The judgment of the Court of Appeal is reversed with directions to affirm the award of summary judgment in defendants’ favor.
George, C. J., Baxter, J., and Brown, J., concurred.