Involuntary Manslaughter Laws Explained

Involuntary manslaughter refers to unintentional homicide that occurs either during the commission of non-felony crimes or during lawful conduct engaged in a reckless manner.

Legal Definition Of Involuntary Manslaughter

 Manslaughter is the unlawful killing of a human being without malice.  It is of three kinds: (b)

  • Involuntary – in the commission of an unlawful act, not amounting to a felony;


  • In the commission of a lawful act which might produce death, in an unlawful manner, 


  • Without due caution and circumspection.  This subdivision shall not apply to acts committed in the driving of a vehicle.

Involuntary manslaughter does not include death that occurs as a result of an act a defendant commits while driving a car.  In California, gross vehicular manslaughter  or negligent vehicular manslaughter and involuntary manslaughter are separate crimes with distinct definitions and punishments.1

Example: Kenneth prescribed a dose of insomnia medication to a patient that was significantly above the dose that was safe.  As a result, the patient died from an overdose.  Prescribing drugs is generally a lawful activity but in this instance, the state will have to prove that Kenneth acted recklessly by prescribing a dose that was not safe.  The state does not need to prove that Kenneth intended to kill the patient.

How Does The Prosecutor Prove Involuntary Manslaughter?

To prove that the defendant is guilty of this crime, the prosecutor must prove that2:

  • The defendant committed an unlawful act (not amounting to a felony)3 or a lawful act in an unlawful manner;
  • The defendant committed the crime or act with criminal negligence4; AND
  • The defendant’s acts caused the death of another person.

Proving “criminal negligence”: Criminal negligence involves more than ordinary negligence. A person acts with criminal negligence when:

  • He or she acts in a reckless way that creates a high risk of death or great bodily injury; AND
  • A reasonable person would have known that acting in that way would create such a risk.

In other words, a person acts with criminal negligence when the way he or she acts is so different from the way an ordinarily careful person would act in the same situation that his or her act amounts to disregard for human life or indifference to the consequences of that act.5

Who Can Be Charged With Involuntary Manslaughter?

Under Penal Code section 192(b), anyone who causes a death of another while acting with:

  • Criminal recklessness or
  • Negligence; or
  • Anyone who causes a death of another that, results during the commission of a misdemeanor or infraction can be charged with involuntary manslaughter.

Example: Jeff wanted to watch his football game.  He went to a sports bar and sat down next to another man Kirk, who was a tennis fanatic.  As Jeff’s game was about to start, Kirk asked the bar tender to change the channel to the tennis channel.

Jeff politely asked the Kirk to switch the channel to the football game but was completely ignored.  Jeff then took out a gun, which is a misdemeanor under California’s brandishing a weapon law, planning merely to threaten Kirk to switch the channel.

But when Kirk saw Jeff displaying a weapon, he unexpectedly jumped at Jeff to try to grab the gun away from him.  As a result, the gun went off accidentally, killing Kirk.  Although Jeff did not have the intent to kill Kirk, the fact that Kirk was shot and killed while Jeff committed a misdemeanor, makes involuntary manslaughter the appropriate charge in this instance.

How Can You Fight Involuntary Manslaughter?

There are several defenses that your attorney can assert on your behalf to fight a charge of involuntary manslaughter.  Here are the most common ones:

  • Self-defense: To succeed on this defense, a defendant must show that the killing resulted from a reasonable use of force to resist a reasonable fear of death or bodily harm.  The degree of force used in self-defense must be proportional to the threat perceived, and the threat perceived must be something that would place a reasonable person in fear of death or great bodily harm.  Mere words or insults do not suffice.

Example: Jane was standing in line at a liquor store while she noticed that two of the customers went to the back of the store and one of them took out a gun while the other one spray-painted the video camera.  The customer with a gun came up to her and told her that if she does not get on her knees with her head to the floor that he would shoot her.  As Jane was about to get on the floor, she grabbed a bottle of beer from the counter and delivered a hard blow to his head, causing him to lose conscience.  If the customer suffered a fatal injury, Jane would not be guilty of murder because she reasonably feared for her life and was justified in using deadly force to prevent the customer from killing her or from inflicting great bodily harm onto her.

  • Defense of others:  The same requirements as for self-defense apply.  The use of force must be timely and proportional to the threat faced, and the perceived threat of death or bodily harm must be reasonable.
  • Imperfect self-defense: A killing that would otherwise be murder is reduced to involuntary manslaughter if the defendant killed a person because he/she acted in imperfect self-defense or imperfect defense of another.  The difference between complete self-defense or defense of another and imperfect self-defense or imperfect defense of another depends on whether the defendant’s belief in the need to use deadly force was reasonable. 6

The defendant acted in imperfect self-defense or imperfect defense of another if:

  • The defendant actually believed that he/she or someone else was in imminent danger of being killed or suffering great bodily injury; AND
  • The defendant actually believed that the immediate use of deadly force was necessary to defend against the danger; BUT
  • At least one of those beliefs was unreasonable.

Example: Sam rode the public bus every night from work.  One night, another patron sat next to him and kept fidgeting.  He then put one hand in his pocket and Sam right away assumed that the patron had a gun in his pocket even though there was no indication that the patron was violent or that he wanted to hurt Sam.  As the patron started pulling his hand out of the pocket, Sam, genuinely but unreasonably believing that his life is in danger, pushed the patron to the floor of the bus while it was moving.  The patron lost balance and hit his head on the adjacent seat and suffered a fatal injury.  On these facts, it was unreasonable for Sam to believe that potentially deadly force was necessary to prevent danger of injury to him.  As a result, this type of imperfect self-defense would not excuse involuntary manslaughter.

  • Accidental killing: An accidental killing committed during lawful events does not meet the requirements of a murder.  However, if an accidental killing occurs during the commission of a crime, it could be considered murder.  Homicide is excusable when committed by accident, or in doing any other lawful act by lawful means, with usual and ordinary caution, and without any unlawful intent. 7
  • The Insanity defense: A defendant can plead not guilty by reason of insanity.  To succeed on this defense under California law, the defendant has to meet the Mc’Naughten test of insanity.  Specifically, he/she has to show that as a result of a mental disorder, he/she either did not know the wrongfulness of his/her act OR could not understand the nature and quality of his/her acts (i.e. did not understand right from wrong).

Example: Harry’s brother and roommate, Jeff suffered from the bipolar disorder and refused to take his medication.  One of the symptoms of his disorder was severe paranoia that everyone is out to kill him.

He also sometimes experienced hallucinations and his condition was getting worst.  One day, Jeff came home and saw a note pad with a pen sitting on his desk.  Because of his severe paranoia, he hallucinated that the pen was a dagger, and imagined that the note pad contained a note for him from Harry that read: “I am going to kill you tonight.

Harry.”  In reality, nothing was written in the note pad.  That night, Jeff went into his brothers’ bedroom in the middle of the night and stabbed him to death with a kitchen knife.  Jeff could plead not guilty by reason of insanity and would likely be found not guilty of murder by reason of insanity on these facts.

  • Mistaken identity: A defendant can use this defense if he believes that the prosecution has charged the wrong person with the murder.  A defendant who uses this defense usually asserts an alibi with supporting evidence to prove that he/she was somewhere else at the time of the murder.

What Are The Penalties, Punishment And Sentencing Guidelines For Involuntary Manslaughter Under Penal Code 1929(b) PC?

Involuntary manslaughter is a felony and a defendant can face up to:

  • 1 year county jail OR
  • 2, 3, or 4-year prison sentence

Additionally, a defendant can face the following additional penalties:

  • Loss of the right to possess a firearm
  • A fee of up to $10,000

Related Offenses

Next Steps If You Need Help

If you have been arrested and would like to learn more about how attorneys charge.

If you want to understand why its important to have an attorney represent you.

If you would like to discuss a pending case with an attorney contact the Aizman Law Firm at 818-351-9555 for a free confidential consultation.

Request A Free Consultation 818-351-9555 


  1. Involuntary Manslaughter Defined. Penal Code 192(b); CALCRIM No. 581. []
  2. Elements. Penal Code 192(b); CALCRIM No. 581. []
  3. An “unlawful act” not amounting to a felony is either a misdemeanor or an infraction.  Unlawful Act Not Amounting to a Felony.  People v. Thompson (2000) 79 Cal.App.4th 40, 53 [93 Cal.Rptr.2d 803]. []
  4. Criminal Negligence Requirement People v. Butler (2010) 187 Cal.App.4th 998, 1014 [114 Cal.Rptr.3d 696].  “The words lack of ‘due caution and circumspection’ [in Pen. Code,  §192(b)] have been heretofore held to be the equivalent of ‘criminal negligence.’” People v. Penny (1955) 44 Cal.2d 861, 879 [285 P.2d 926]. []
  5. Criminal Negligence Requirement People v. Butler (2010) 187 Cal.App.4th 998, 1014 [114 Cal.Rptr.3d 696]. []
  6. CALCRIM No. 581. []
  7. Pen. Code §195. []

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