Study guide
8.2 Criminal Causation & Intervening Causes
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1 Introduction & FYLSE Examination Guide
1.1 FYLSE Exam Structure, Passing Standard & Administration 1.2 Study Method, Pacing & MBE-Style Technique
2 Contracts: Mutual Assent, Capacity & Contract Formation
2.1 The Offer & Objective Theory of Assent 2.2 Termination & Irrevocability of Offers 2.3 Acceptance & the Mailbox Rule 2.4 Mirror Image Rule & UCC 2-207 Battle of the Forms 2.5 Mistake in Contract Formation 2.6 Fraud, Duress, Undue Influence & Illegality 2.7 Capacity to Contract
3 Contracts: Consideration, Estoppel & Implied Obligations
3.1 Consideration & the Bargained-For Exchange 3.2 Past & Moral Consideration, Pre-Existing Duty & Modification 3.3 Promissory Estoppel & Detrimental Reliance 3.4 Implied-in-Fact Contracts & Quasi-Contract 3.5 Implied Covenant of Good Faith, Fair Dealing & Indefinite Terms
4 Contracts: Third-Party Beneficiaries, Assignment & Delegation
4.1 Third-Party Beneficiary Contracts 4.2 Assignment of Rights 4.3 Delegation of Duties
5 Contracts: Statute of Frauds, Parol Evidence & Interpretation
5.1 Statute of Frauds: Contracts Within the Statute 5.2 Satisfying the Statute: Writing, Signature & Exceptions 5.3 The Parol Evidence Rule 5.4 Contract Interpretation & Canons of Construction
6 Contracts: Performance, Conditions, UCC Warranties & Breach
6.1 Conditions: Express, Constructive & Excuse 6.2 Substantial Performance vs. Perfect Tender 6.3 Cure, Rejection, Revocation & Installment Contracts 6.4 UCC Article 2 Warranties & Risk of Loss 6.5 Anticipatory Repudiation & Insecurity
7 Contracts: Remedies, Discharge & Changed Circumstances
7.1 Expectation Damages & Their Limitations 7.2 Reliance, Restitution & Liquidated Damages 7.3 Specific Performance & Injunctive Relief 7.4 UCC Article 2 Buyer's and Seller's Remedies 7.5 Impossibility, Impracticability & Frustration of Purpose 7.6 Discharge by Agreement: Rescission, Novation & Accord and Satisfaction
8 Criminal Law: Principles of Criminal Liability & Mens Rea
8.1 Actus Reus, Voluntary Acts & Omissions 8.2 Criminal Causation & Intervening Causes 8.3 Common Law & Model Penal Code Mens Rea 8.4 Mistake of Fact, Mistake of Law & Concurrence
9 Criminal Law: Inchoate Offenses & Accomplice Liability
9.1 Criminal Attempt & Impossibility 9.2 Solicitation & the Merger Doctrine 9.3 Conspiracy & Merger Doctrine 9.4 Accomplice Liability: Actus Reus & Mens Rea 9.5 Scope of Accomplice Liability, Withdrawal & Parties to Crime
10 Criminal Law: Homicide & Crimes Against the Person
10.1 Common Law Murder & Malice Aforethought 10.2 Degrees of Murder, Premeditation & Deliberation 10.3 The Felony Murder Rule & Its Limitations 10.4 Voluntary & Involuntary Manslaughter 10.5 Non-Homicide Crimes Against the Person
11 Criminal Law: Property Crimes, Theft & Habitation
11.1 Common Law Larceny 11.2 Embezzlement & False Pretenses 11.3 Robbery & Extortion 11.4 Receiving Stolen Property 11.5 Burglary 11.6 Arson
12 Criminal Law: Defenses: Capacity, Justification & Excuse
12.1 Insanity: The Four Legal Tests 12.2 Intoxication, Diminished Capacity & Infancy 12.3 Self-Defense & Defense of Others 12.4 Defense of Property, Habitation & Law Enforcement Privileges 12.5 Duress & Necessity 12.6 Entrapment & Mistake as an Excuse
13 Torts: Intentional Torts to Persons & Property
13.1 Intent, Motive & Incapacity in Intentional Torts 13.2 Transferred Intent 13.3 Battery & Assault 13.4 False Imprisonment 13.5 Trespass to Land 13.6 Trespass to Chattels & Conversion
14 Torts: Privileges & Defenses to Intentional Torts
14.1 Consent: Express, Implied & Capacity 14.2 Exceeding & Vitiating Consent 14.3 Self-Defense & Defense of Others (Tort) 14.4 Defense of Property & Recapture of Chattels 14.5 Public & Private Necessity 14.6 The Shopkeeper's Privilege
15 Torts: Negligence — Duty of Care & Breach
15.1 Duty of Care & the Foreseeable Plaintiff 15.2 Affirmative Duties to Act & Special Relationships 15.3 Standard of Care: The Reasonable Person & Children 15.4 Professional Negligence, Informed Consent & Negligence Per Se 15.5 Land Possessor Liability & Premises Duties 15.6 Breach of Duty & Res Ipsa Loquitur
16 Torts: Causation, Defenses, Multiple Tortfeasors, Wrongful Death & Damages
16.1 Cause in Fact & Multiple Actors 16.2 Proximate Cause & Intervening Forces 16.3 Contributory, Comparative Negligence & Assumption of Risk 16.4 Joint and Several Liability, Contribution & Indemnity 16.5 Vicarious Liability & Non-Delegable Duties 16.6 Wrongful Death & Survival Actions 16.7 Statute of Limitations & Claim Accrual 16.8 Tort Damages: Compensatory, Nominal, Punitive & Mitigation
17 Torts: Strict Liability & Products Liability
17.1 Strict Liability for Animals 17.2 Abnormally Dangerous Activities & Scope of Risk 17.3 Strict Products Liability & Defect Categories 17.4 Products Liability Under Negligence, Warranty & Misrepresentation 17.5 Defenses to Products Liability
18 Torts: Emotional Distress, Defamation, Privacy & Economic Torts
18.1 Intentional Infliction of Emotional Distress 18.2 Negligent Infliction of Emotional Distress 18.3 Common Law Defamation: Elements, Libel & Slander 18.4 Constitutional Limits, Privileges & Defenses to Defamation 18.5 Invasion of Privacy 18.6 Nuisance & Economic Torts
8.2 Criminal Causation & Intervening Causes
Key Takeaways Explain This Topic AI
Actual cause asks whether the result would have occurred but for the defendant's conduct, with the substantial factor test covering multiple sufficient causes.
Proximate cause asks whether the result is so related to the defendant's conduct that it is fair to impose liability, which turns on foreseeability.
A dependent intervening cause responds to the defendant's conduct and breaks the chain only if abnormal or bizarre, so ordinary medical negligence does not relieve the defendant.
An independent intervening cause is coincidental and breaks the chain unless it was foreseeable.
The eggshell-skull principle applies in criminal law too, so a defendant takes the victim's pre-existing frailties as he finds them.
Last updated: September 2026
- Criminal Causation & Intervening Causes
- 1. Causation: Actual Cause & Proximate Cause
In all "result crimes" (offenses where the statutory definition requires a specific prohibited result, such as homicide, battery, or arson), the prosecution must establish two independent causation prongs beyond a reasonable doubt: Cause-in-Fact (Actual Cause) and Proximate Cause (Legal Cause) .
Cause-in-Fact (Actual Cause)
Cause-in-fact establishes the physical, historical connection between the defendant's actus reus and the resulting harm. Courts employ three distinct tests to resolve cause-in-fact:
The "But-For" (Sine Qua Non) Test: The standard baseline test: But for the defendant's physical act, would the prohibited harm have occurred when and as it did? If the harm would have occurred at the same time and in the same manner regardless of the defendant's conduct, the defendant is not a but-for cause.
The Substantial Factor Test (Concurrent Sufficient Causes): Where two independent actors, acting without conspiracy or concert, inflict simultaneous mortal injuries upon a victim, and either injury alone was sufficient to produce instantaneous death (e.g., D1 shoots V through the heart while D2 simultaneously shoots V through the brain), neither wound passes the strict "but-for" test in isolation. To prevent both killers from escaping liability, the law applies the substantial factor test : both D1 and D2 are actual causes because each defendant's physical act was a substantial factor in bringing about the death.
The Acceleration of Death Doctrine: Under common law homicide principles, death is inevitable for all living beings; therefore, homicide law punishes the unlawful acceleration of death . If a victim is already mortally wounded by poison or suffering from a terminal disease with only hours to live, an actor who shoots, stabs, or suffocates the victim—hastening death by even five minutes—is the cause-in-fact of the homicide.
Proximate Cause (Legal Cause)
Proximate cause is an objective policy determination assessing whether it is fair, just, and foreseeable to hold the defendant criminally responsible for the prohibited result. Proximate cause exists when the harm is the natural, direct, and probable consequence of the defendant's conduct, falling within the foreseeable zone of risk created by the actor.
The "Eggshell Skull" (Thin Skull) Rule
In criminal law, as in torts, the defendant takes their victim as they find them. Pre-existing physical frailties, hidden medical vulnerabilities, and psychological or religious idiosyncrasies do not sever proximate causation:
Hemophilia / Heart Conditions: If D inflicts a non-fatal blow that would merely bruise an ordinary person, but V suffers from rare hemophilia and bleeds to death, D is the proximate cause of V's death.
Religious Refusal of Medical Treatment: If D shoots V, and V subsequently refuses a life-saving blood transfusion due to sincere religious beliefs (such as Jehovah's Witness tenets), V's refusal does not sever the causal chain. D remains criminally liable for homicide because D placed V in the position of requiring medical intervention.
2. Intervening Causes: Dependent vs. Independent (Superseding)
An intervening cause is an independent or dependent force (human act, animal action, or natural event) that enters the causal chain after the defendant's initial act and contributes to the ultimate harm. The dispositive issue on the FYLSE is whether the intervening force breaks the chain of proximate causation, thereby functioning as a superseding cause that relieves the defendant of liability for the ultimate result. [ Defendant's Act ] ──▶ [ Intervening Force ] ──▶ [ Prohibited Result ]
- │
- ┌──────────────────────┴──────────────────────┐
- ▼ ▼
- [ Dependent / Foreseeable ] [ Independent / Unforeseeable ]
- Does NOT break causal chain SUPERSEDING CAUSE
- Defendant LIABLE for result Defendant EXCUSED from result
- Dependent Intervening Forces (Foreseeable Responses)
A dependent intervening force is an act or event that occurs in natural response to, or is provoked by, the defendant's original unlawful conduct. Because dependent forces are deemed reasonably foreseeable, they DO NOT break the chain of proximate causation.
Ordinary Medical Negligence: When a defendant inflicts physical injury requiring medical intervention, ordinary medical negligence (e.g., misdiagnosis, minor surgical error, delayed treatment, or hospital-acquired bacterial infection) is deemed foreseeable as a matter of law. Even though the physician's negligence accelerated death, the defendant remains fully liable for homicide.
Victim's Flight and Self-Preservation: If a victim, reasonably attempting to escape the defendant's violent assault, jumps from a second-story window, flees into traffic, or drowns while swimming across a river, the victim's instinctive reaction is a foreseeable dependent response. The defendant is the proximate cause of the resulting death.
Rescuer's Negligence: Under the doctrine that danger invites rescue , normal, non-reckless errors committed by emergency responders or civilian rescuers attempting to aid the victim do not sever proximate causation.
Independent Intervening Forces (Superseding Causes)
An independent intervening force operates completely independently of the defendant's conduct and is not triggered by it. If an independent intervening cause is extraordinary, abnormal, and unforeseeable , it constitutes a superseding cause that breaks proximate causation. The defendant is relieved of liability for the ultimate result, though the defendant remains guilty of inchoate offenses (such as attempt) or completed lesser crimes (such as battery).
Gross Medical Negligence / Reckless Malpractice: While ordinary negligence is foreseeable, gross, reckless, or abnormal medical malpractice (e.g., an intoxicated surgeon administering a massive lethal overdose of an unrelated, contraindicated drug, or hospital staff deliberately turning off life support without authorization) constitutes an unforeseeable superseding cause.
Acts of God / Extraordinary Natural Catastrophes: If D shoots V in the leg and leaves V on an open park bench, and a sudden freak bolt of lightning strikes and incinerates V, the natural catastrophe is an independent superseding cause.
Unforeseen Third-Party Intentional Felonies: If D non-fatally wounds V, and an unrelated enemy of V enters the hospital recovery ward and shoots V through the head, the independent intentional assassination breaks proximate causation as to D.
Intervening Force Type Example Event Breaks Causal Chain? Resulting Defendant Liability
Dependent / Foreseeable Doctor negligently prescribes incorrect antibiotic for gunshot wound; V dies of sepsis. No Liable for Homicide (Murder or Manslaughter).
Dependent / Foreseeable V leaps from moving vehicle to escape D's armed robbery; V dies on highway impact. No Liable for Felony Murder.
Independent / Foreseeable D leaves an unconscious victim on an unlit road at night; passing motorist strikes V. No Liable for Homicide (Motorist was foreseeable consequence of peril).
Independent / Unforeseeable Ambulance transporting wounded V to hospital is struck by an airplane crash. Yes (Superseding) Attempted Homicide or Battery only; relieved of Homicide.
Gross Medical Malpractice Surgeon amputates wrong organ during routine wound cleansing; V bleeds to death. Yes (Superseding) Battery or Attempted Murder only; medical gross negligence supersedes.
- 3. The Common Law "Year-and-a-Day" Rule vs. Modern Trend
- The Common Law Rule
Under ancient English common law, if a victim did not die within a year and a day (366 calendar days) after the infliction of the mortal wound or injury, the law established an irrebuttable presumption that death was attributable to natural causes, old age, or intervening disease rather than the defendant's act. Prosecution for murder or manslaughter was absolutely barred, regardless of how clearly modern medical pathology could trace causation.
Modern Abolition and California Penal Code § 194
Advances in modern medical technology, life support, and forensic science have rendered the common-law year-and-a-day rule obsolete. Today, the vast majority of jurisdictions have completely abolished the temporal bar.
In California, California Penal Code § 194 previously retained a modified temporal rule, but the California Legislature amended the statute to eliminate the strict bar. Under current California law, the prosecution may maintain a homicide charge regardless of how much time elapses between the assault and the victim's death, provided that if death occurs beyond three years and a day , a rebuttable presumption arises that the death was not the result of the criminal act, which the prosecution may overcome with clear medical proof.