Master California Court of Appeal decision on proximate cause in a homicide prosecution where two police helicopters collided during a pursuit. with this comprehensive case brief.
People v. Acosta is a staple case in criminal law courses for its treatment of proximate cause in homicide, especially where intervening acts by third parties contribute to the fatal result. The facts are dramatic: a high-speed police chase that drew airborne support and ended with a midair collision between two police helicopters, killing multiple officers. The legal question is equally striking: can a fleeing driver be held criminally responsible for deaths resulting from a helicopter collision that occurred during the chase he set in motion?
The Court of Appeal used Acosta to articulate a principled, tort-informed approach to criminal proximate cause. Borrowing from the Restatement and prior California cases, the court emphasized that intervening acts of rescuers and law enforcement are generally foreseeable responses to dangerous conduct. The decision anchors the idea that a defendant remains liable unless the intervening event is so highly unusual as to be considered highly extraordinary in retrospect, while also clarifying that proximate cause and malice are distinct inquiries in a murder prosecution.
11 Cal. App. 4th 1276, 15 Cal. Rptr. 2d 473 (Cal. Ct. App. 1992)
Acosta led police on an extended, high-speed vehicular chase through Orange County, California, driving recklessly through city streets and freeways, running lights, and narrowly avoiding collisions. Multiple agencies joined the pursuit, including ground units and two law enforcement helicopters that coordinated overhead to track and manage the chase. During the ongoing pursuit, the two police helicopters converged and collided midair while maneuvering in the same airspace, causing a crash that killed members of the flight crews. Acosta was prosecuted, inter alia, for second-degree murder based on implied malice, with the prosecution alleging that his flight proximately caused the helicopter deaths. On appeal, Acosta argued that the helicopter collision was an unforeseeable, superseding cause and that the evidence did not support implied malice for second-degree murder.
In a homicide prosecution arising from a high-speed police pursuit, does a fleeing driver proximately cause the deaths of officers when two pursuing police helicopters collide, or does the midair collision constitute a superseding cause that breaks the chain of criminal causation?
A defendant is criminally liable for homicide if his conduct is a substantial factor in bringing about the victim’s death and the result is not so highly unusual or extraordinary in retrospect as to be outside the scope of the risk created. Intervening acts by third parties, including the negligent or mistaken responses of law enforcement or rescuers, do not relieve the defendant of liability unless they are independent, unforeseeable, and so abnormal as to constitute a superseding cause. California courts often articulate this in terms drawn from tort law and the Restatement (Second) of Torts, including the highly extraordinary in retrospect standard. Separately, second-degree implied malice murder requires proof that the defendant acted with a conscious disregard for human life, meaning a subjective awareness that his conduct endangers life and a deliberate decision to act despite that knowledge.
The helicopter collision was not, as a matter of law, a superseding cause that broke the chain of causation; there was sufficient evidence from which a jury could find that Acosta’s reckless flight was a proximate cause of the deaths because the involvement of police air support and the risk of collision were not highly extraordinary in retrospect. However, the court concluded that the evidence was insufficient to establish implied malice for second-degree murder as to the helicopter occupants and reversed the second-degree murder convictions, remanding for further proceedings consistent with its opinion.
The court began by distinguishing factual cause from proximate cause. Acosta’s conduct indisputably set in motion the police response, including the aerial pursuit, and was a substantial factor in creating the circumstances that led to the collision. The central dispute was whether the midair collision constituted a superseding cause. Drawing on the Restatement (Second) of Torts and California precedent, the court explained that the foreseeability question in proximate cause is not whether the specific manner of harm was predictable in fine detail, but whether the general kind of harm fell within the scope of risk created by the defendant’s conduct. Police pursuit, including the use of helicopters, is a normal and foreseeable response to a dangerous flight, and it is not highly extraordinary that multiple aircraft operating in close quarters under the stresses of a live pursuit might collide. Even if pilot error or miscommunication contributed, such negligence by responders is a dependent intervening act within the very risk the defendant created and does not break causation. At the same time, the court treated malice as a separate inquiry. Implied malice requires a subjective awareness that one’s conduct endangers human life and a deliberate disregard of that risk. While the record supported that Acosta consciously disregarded the risk to motorists and officers on the ground, the prosecution did not present sufficient evidence that he subjectively appreciated the lethal risk to persons in helicopters from a potential midair collision. Awareness that helicopters were overhead did not, without more, establish the requisite conscious disregard for the particular life-threatening danger that materialized. Thus, the causal link sufficed for criminal liability, but the mental state evidence did not support second-degree murder as charged.
Acosta is a leading California case aligning criminal proximate cause analysis with tort principles. It reinforces that the negligent responses of law enforcement or rescuers are ordinarily foreseeable and do not, without being highly extraordinary, sever the causal chain. For students, the case highlights the separate roles of causation and mens rea: a defendant can proximately cause a death without necessarily possessing the malice needed for murder. The decision offers a durable framework for exam analysis where unusual intervening events occur during pursuits, rescues, or medical treatment following a defendant’s dangerous act.
The court applied a tort-informed proximate cause framework drawn from the Restatement (Second) of Torts, focusing on whether the result was highly extraordinary in retrospect. Because police helicopter involvement is a foreseeable response to a high-speed chase, and a collision between aircraft operating in close proximity is not highly extraordinary, the collision was not a superseding cause.
No. Even if pilot error contributed, such negligence is a dependent intervening act that falls within the scope of risk created by Acosta’s dangerous flight and is therefore foreseeable. Dependent intervening acts typically do not break the chain unless they are so abnormal and unforeseeable as to be highly extraordinary.
Because implied malice requires a subjective awareness of the danger to human life and a conscious disregard of that risk. The court concluded the evidence did not show Acosta subjectively appreciated the lethal risk to helicopter occupants from a potential midair collision, even though his conduct proximately caused the deaths. Thus, causation was present but malice was not.
Acosta is consistent with cases like People v. Armitage and later pursuit cases that treat responder negligence as foreseeable and apply a substantial factor and scope-of-risk analysis. The case solidifies that California criminal courts borrow tort proximate cause concepts, while keeping mens rea requirements distinct for offenses like murder.
Identify factual cause, then analyze proximate cause by asking whether the intervening act is dependent and foreseeable, and whether the outcome is highly extraordinary in retrospect. Separately analyze mens rea for the charged offense. Acosta is especially helpful where responders or rescuers act negligently during a pursuit or rescue.
People v. Acosta teaches that criminal liability for homicide can extend through complex chains of events so long as the defendant’s conduct is a substantial factor and the resulting harm is not highly extraordinary in retrospect. Police responses, including the use of helicopters, are foreseeable reactions to dangerous conduct and ordinarily do not sever causation even if negligence is involved.
The case also underscores that proximate cause and malice are different elements. While Acosta’s flight proximately caused the officers’ deaths, the prosecution failed to prove the subjective awareness and conscious disregard necessary for implied malice murder. For students and practitioners, Acosta provides a clear template for analyzing causation without conflating it with mental state requirements.