In a felony murder prosecution, proximate cause is the test that decides whether a death counts as the defendant’s responsibility. It asks whether the killing was a reasonably foreseeable consequence of the felony the defendant chose to commit. If it was, the defendant can be charged with murder even when someone else — a victim, a police officer, a bystander — fired the fatal shot. If the death was too freakish or disconnected from the crime to be foreseen, the causal chain breaks and felony murder liability falls away.
That single question does an enormous amount of work. It is the reason a getaway driver can face a life sentence for a shooting he never saw coming, and the reason a robber in one state is charged with murder for a death caused by police while a robber in another state is not.
Two Causation Tests, One That Actually Matters
Criminal law uses two causation questions. The first, “but-for” causation, asks whether the victim would have died if the defendant had not acted. That test sweeps in almost anything. A robber’s parents are a but-for cause of the robbery; nobody thinks that makes them liable.
Proximate cause does the real filtering. Federal jury instructions describe it as a cause that “played a substantial part in bringing about the death, so that the death was the direct result or a reasonably probable consequence of the defendant’s act.”1Ninth Circuit District & Bankruptcy Courts. Manual of Model Criminal Jury Instructions – 8.110 Manslaughter—Involuntary Freak coincidences fall out. Reasonably predictable consequences stay in. Without proximate cause, a prosecutor who can show but-for causation still has no legal link strong enough to support a homicide charge; the defendant may answer for the underlying felony, but not for the death.
Agency Theory vs. Proximate Cause Theory
States split sharply on how proximate cause operates in felony murder cases, and the split changes the identity of who can be charged.
Agency Theory
Under the agency theory, the fatal act must be committed by one of the participants in the felony. If two people rob a bank and one shoots the teller, both are liable for murder. If a responding officer accidentally kills a bystander in the same confrontation, the robbers are not liable for that death. The officer is not acting as the robbers’ agent. A majority of states follow this narrower framework.
Proximate Cause Theory
The proximate cause theory holds defendants responsible for any death that is a foreseeable result of the felony, regardless of who caused it. If a homeowner fires at burglars and accidentally kills a neighbor, the burglars can be charged with felony murder because they set the dangerous chain of events in motion. Deaths caused by victims, bystanders, and law enforcement all count. The exposure in these jurisdictions is substantially broader, and arguments about proximate cause carry most of the weight at trial.
Foreseeability and Superseding Causes
Even in proximate cause jurisdictions, liability has outer limits. When something intervenes between the felony and the death, courts ask whether that intervening event was foreseeable or so extraordinary that it severs the causal link entirely. An unforeseeable, extraordinary event is called a superseding cause, and it ends the defendant’s responsibility for the death.
What Courts Treat as Foreseeable
Most intervening events do not break the chain. A robbery victim who gets negligent medical treatment and dies from the combined effect of the gunshot wound and the medical error remains a felony murder case. Medical negligence is treated as a foreseeable complication of inflicting serious injury. The same reasoning covers a victim who flees the scene and is struck by a car, and police use of deadly force to stop fleeing felons. These are predictable results of committing a violent crime.
What Counts as Superseding
A superseding cause has to be genuinely bizarre. The textbook example is a victim taken to the hospital for minor injuries from a robbery whose building then collapses from a structural defect. The victim would not have been there but for the robbery, but a building collapse is so disconnected from the crime that it severs the causal link. Cases this clean are rare, but the principle sets the ceiling: felony murder liability, even under the broadest theory, is not unlimited.
Deaths During Escape
Felony murder reaches deaths that occur “during the commission” of the predicate crime, and courts read that phrase generously. The felony continues as a “continuous transaction” until the participants reach a place of temporary safety. A death at a roadblock, during a car chase, or in the getaway car’s crash is still within the window. Only when the defendants reach a place where they are no longer in immediate flight does the felony murder window close.
Proximate cause carries this through. A bystander killed when the fleeing car runs a light is a foreseeable consequence of the robbery, so the robbers can be charged with that death even though the robbery itself was technically complete.
When the Person Who Dies Is a Co-Felon
A recurring question is whether a defendant can be charged with felony murder when the person killed is a fellow participant. If two people rob a store and the owner shoots one of them, can the surviving robber be charged with murdering his partner?
The answer tracks the agency/proximate cause divide. Some jurisdictions carve out an exception for co-felon deaths, reasoning that the felony murder rule is meant to protect innocent people. Others, particularly those using the proximate cause theory, allow the charge because the surviving felon’s decision to commit the crime foreseeably created the risk that produced the death.
Attacking Proximate Cause as a Defense
Causation is often the most promising line of defense in a felony murder case, especially when the defendant did not personally kill anyone. The arguments fall into a few categories.
- The death was not a reasonably foreseeable consequence of the felony.
- A superseding event broke the causal chain between the crime and the death.
- In agency theory jurisdictions, the fatal act was committed by someone outside the criminal group.
- The felony had ended — the participants had reached a place of temporary safety — before the death occurred.
Some states also recognize a narrow affirmative defense for co-felons who can show they were not the killer, were not armed, had no reason to believe any co-felon was armed or intended violence, and did not personally engage in conduct that caused the death. The burden sits on the defendant, and the requirements are strict.
Withdrawal from the felony before the killing can also eliminate liability, but only if the withdrawal is complete and timely. Courts generally require the defendant to clearly communicate the withdrawal to co-felons, and in some jurisdictions to take affirmative steps to stop the crime, such as alerting police. Expressing reluctance while staying at the scene is not withdrawal.
Constitutional Ceiling for Non-Killers
Proximate cause can make a non-killer eligible for a felony murder conviction, but the Eighth Amendment sets a separate limit on how severely that defendant can be punished when the death penalty is on the table.
In Enmund v. Florida, the Supreme Court held that executing a defendant who “aids and abets a felony in the course of which a murder is committed by others but who does not himself kill, attempt to kill, or intend that a killing take place” violates the ban on cruel and unusual punishment. Earl Enmund was the getaway driver in a robbery where his co-felons killed two people. The Court concluded that putting him to death “to avenge two killings that he did not commit and had no intention of committing or causing does not measurably contribute to the retributive end of ensuring that the criminal gets his just deserts.”2Legal Information Institute. Enmund v Florida, 458 US 782
Five years later, in Tison v. Arizona, the Court allowed the death penalty for non-killers who were “major participants” in the underlying felony and acted with “reckless indifference to human life.” The Tison brothers helped their father escape from prison, armed the escape group, and were present at a roadblock where their father and another escapee murdered a family of four. The Court noted that these requirements often overlap: “the greater the defendant’s participation in the felony murder, the more likely that he acted with reckless indifference to human life.”3Justia. Tison v Arizona, 481 US 137 (1987)
Together these cases set a two-part constitutional standard for capital felony murder of a non-killer: major participation plus reckless indifference. The standard governs the death penalty only. A defendant who played a minor role can still receive a life sentence for felony murder without violating the Eighth Amendment.
Reforms Narrowing the Rule
Several jurisdictions have cut back on felony murder. Kentucky, Hawaii, and Ohio abolished the doctrine by statute. Michigan’s courts eliminated it by judicial decision.
California’s SB 1437 made one of the most significant recent changes. Under the revised law, a participant in a qualifying felony is liable for murder only if they were the actual killer, aided the killer with the intent to kill, or were “a major participant in the underlying felony and acted with reckless indifference to human life.” The statute also provides that malice “shall not be imputed to a person based solely on his or her participation in a crime.”4LegiScan. Bill Text: CA SB1437 – 2017-2018 – Regular Session – Chaptered The practical effect is that California applied the Tison standard across the board, not just in death penalty cases, and created a resentencing process for people convicted under the old rule.
The common thread across these reforms is a judgment that proximate cause alone sweeps too widely, pulling in defendants whose actual role in a death does not match a murder conviction. Whether more states follow is unsettled, but the direction of recent change has been toward tightening the link between what a defendant did and the killing they are held to answer for.