I have been reading and seeing some fiction where it was shown that a thief breaks into a house, steals, he is caught in the act, in the struggle, there is a blow to the head and the thief dies. The thief had knife and there were woman and children present.

Ignoring self-defense, does this situation have the elements of involuntary manslaughter?

  • 1
    Surely the presence of women or children is irrelevant (unless perhaps the fatal blow were struck by a woman or child).
    – phoog
    Jan 13, 2017 at 4:17
  • @phoog: That would depend on the jurisdiction. Can self defense be claimed, when defending not yourself but family members? I.e. if I could reasonably flee, I might not be able to claim self defense, but my children might not be able to flee which leaves me with a moral duty to defend them - a duty I wouldn't have vis a vis any other person.
    – MSalters
    Jan 13, 2017 at 20:08
  • 5
    @MSalters, the self defense defense generally includes defense of others, not just family.
    – user6726
    Jan 14, 2017 at 3:08
  • In some locales this would be deemed praiseworthy manslaughter.
    – EvilSnack
    Jul 9, 2019 at 4:19

4 Answers 4


The name given to different grades of homicide offenses differs considerably from state to state. Colorado, whose penal code is based loosely on the Model Penal Code, does not have an offense called "involuntary manslaughter" and the definition of "involuntary manslaughter" would not be uniform from state to state that does use that term, although there would be some similarities.

Colorado has six homicide offenses that do not involve children (which is the offense of child abuse causing death) or especially vulnerable individuals like the elderly, or kidnapping where the victim is not found in which murder is conclusively presumed, which I list with the pertinent language (omitting, for example, language on what class of felony it is except when necessary to explain substantively different suboffenses):

§ 18-3-102. Murder in the first degree

(1) A person commits the crime of murder in the first degree if:

(a) After deliberation and with the intent to cause the death of a person other than himself, he causes the death of that person or of another person; or

(b) Acting either alone or with one or more persons, he or she commits or attempts to commit arson, robbery, burglary, kidnapping, sexual assault as prohibited by section 18-3-402, sexual assault in the first or second degree as prohibited by section 18-3-402 or 18-3-403 as those sections existed prior to July 1, 2000, or a class 3 felony for sexual assault on a child as provided in section 18-3-405(2), or the crime of escape as provided in section 18-8-208, and, in the course of or in furtherance of the crime that he or she is committing or attempting to commit, or of immediate flight therefrom, the death of a person, other than one of the participants, is caused by anyone; or

(c) By perjury or subornation of perjury he procures the conviction and execution of any innocent person; or

(d) Under circumstances evidencing an attitude of universal malice manifesting extreme indifference to the value of human life generally, he knowingly engages in conduct which creates a grave risk of death to a person, or persons, other than himself, and thereby causes the death of another; or

(e) He or she commits unlawful distribution, dispensation, or sale of a controlled substance to a person under the age of eighteen years on school grounds as provided in section 18-18-407(2), and the death of such person is caused by the use of such controlled substance; or

(f) The person knowingly causes the death of a child who has not yet attained twelve years of age and the person committing the offense is one in a position of trust with respect to the victim.

(2) It is an affirmative defense to a charge of violating subsection (1)

(b) of this section that the defendant:

(a) Was not the only participant in the underlying crime; and

(b) Did not commit the homicidal act or in any way solicit, request, command, importune, cause, or aid the commission thereof; and

(c) Was not armed with a deadly weapon; and

(d) Had no reasonable ground to believe that any other participant was armed with such a weapon, instrument, article, or substance; and

(e) Did not engage himself in or intend to engage in and had no reasonable ground to believe that any other participant intended to engage in conduct likely to result in death or serious bodily injury; and

(f) Endeavored to disengage himself from the commission of the underlying crime or flight therefrom immediately upon having reasonable grounds to believe that another participant is armed with a deadly weapon, instrument, article, or substance, or intended to engage in conduct likely to result in death or serious bodily injury.

(1)(a) is murder with pre-mediation.

(1)(b) and (2) pertain to "felony-murder"

(1)(d) is called deliberate indifference murder.

§ 18-3-103. Murder in the second degree

(1) A person commits the crime of murder in the second degree if the person knowingly causes the death of a person.

(2) Diminished responsibility due to self-induced intoxication is not a defense to murder in the second degree.

(3) (a) Except as otherwise provided in paragraph (b) of this subsection (3), murder in the second degree is a class 2 felony.

(b) Notwithstanding the provisions of paragraph (a) of this subsection (3), murder in the second degree is a class 3 felony where the act causing the death was performed upon a sudden heat of passion, caused by a serious and highly provoking act of the intended victim, affecting the defendant sufficiently to excite an irresistible passion in a reasonable person; but, if between the provocation and the killing there is an interval sufficient for the voice of reason and humanity to be heard, the killing is a class 2 felony.

Subsection (3) is commonly known as "heat of passion" murder.

§ 18-3-104. Manslaughter

(1) A person commits the crime of manslaughter if:

(a) Such person recklessly causes the death of another person; or

(b) Such person intentionally causes or aids another person to commit suicide.

There is also an omitted manslaughter exception for terminating life support, DNR orders and hospice type treatment.

Manslaughter is a class 4 felony (there are six classes of felony with class 1 being first degree murder in most cases, class 2 being most cases of second degree murder, and class 5 and 6 reserved for less serious felony offenses).

§ 18-3-105. Criminally negligent homicide

Any person who causes the death of another person by conduct amounting to criminal negligence commits criminally negligent homicide[.]

Criminal negligence is defined in the statute and caselaw as more serious than negligence in a civil action and is basically akin to the civil lawsuit notion of "gross negligence."

§ 18-3-106. Vehicular homicide

Suffice it to say that the murder weapon must be a vehicle.

§ 18-3-107. First degree murder of a peace officer, firefighter, or emergency medical service provider

Suffice it to say that this is first degree murder as shown above when the victim is a peace officer, firefighter or EMS provider.


Clearly this individual wasn't a peace officer, firefights, or EMS provider, and wasn't killed with a vehicle, so the last two are out.

Clearly, none of the first degree murder categories applies. This wasn't premeditated, the homeowner wasn't trying to commit a felony, there was no perjury, the victim wasn't under the age of twelve, no drugs were involved, and this wasn't a case of deliberate indifference (e.g. shooting randomly into a crowd of people).

This was not a case of criminally negligence, as the thief's death wasn't simply due to a blameworthy accident.

There is a good argument that, but for self-defense, this would be a heat of passion second degree murder. If the circumstances in the struggle were that the homeowner intended to and did kill the thief, this would apply.

There is also an argument that this would be manslaughter, if the homeowner knew that there was a real chance that the thief would be killed but didn't know that this is what would happen and was only actually trying to knock him out, for example.

Implications Of Offense Of Conviction

This subtle distinction between an intent to kill and an intent to not kill with a recognition that death could result, matters quite a great deal.

The presumptive sentence for heat of passion murder is six to twenty-four years in prison (as determined by the judge) followed by five years of supervised release. This can be reduced by up to 25% for good behavior in prison, so the range is effectively 4.5 to 16 years in prison.

The presumptive sentence for manslaughter is two to six years in prison (as determined by the judge) followed by three years of supervised release. This can be reduced by up to 50% for good behavior in prison, so the range is effectively 1 to 3 years in prison.

Post-script On Self-Defense

Of course, this is almost surely actually a case where self-defense applies. But, as the comment to the other answer notes, analytically, that is a separate consideration and not part of the prima facie elements of the crime. If self-defense applies, the result is an acquittal of all charges.

In Colorado, the self-defense provision applicable in this fact pattern is as follows (omitting provisions inapplicable in this fact pattern):

§ 18-1-704.5. Use of deadly physical force against an intruder

(1) The general assembly hereby recognizes that the citizens of Colorado have a right to expect absolute safety within their own homes.

(2) Notwithstanding the provisions of section 18-1-704, any occupant of a dwelling is justified in using any degree of physical force, including deadly physical force, against another person when that other person has made an unlawful entry into the dwelling, and when the occupant has a reasonable belief that such other person has committed a crime in the dwelling in addition to the uninvited entry, or is committing or intends to commit a crime against a person or property in addition to the uninvited entry, and when the occupant reasonably believes that such other person might use any physical force, no matter how slight, against any occupant.

(3) Any occupant of a dwelling using physical force, including deadly physical force, in accordance with the provisions of subsection (2) of this section shall be immune from criminal prosecution for the use of such force.

(4) Any occupant of a dwelling using physical force, including deadly physical force, in accordance with the provisions of subsection (2) of this section shall be immune from any civil liability for injuries or death resulting from the use of such force.

Also, it isn't impossible to imagine a fairly plausible scenario where self-defense isn't available.

For example, suppose it was Halloween or April Fool's Day, and that the apparent intruder was actually an actor hired by the wife as a practical joke. Suppose further that the wife was screaming at the husband while he was battling the intruder "Stop! That's just Fred, an actor, this is just a joke." Suppose that husband heard his wife, but had leapt into such a focused on survival mode adrenaline filled state that while he heard those words and even though a reasonably person in his circumstances would have understood those words, the true meaning of what his wife was saying to him just didn't sink in for him subjectively until it was too late.

Also, in this situation, the wife, might, in addition to the husband, be guilty of criminally negligent homicide, since from her perspective, in this scenario, the death was due to her blameworthy negligence.

In a case like that, an analysis of which underlying homicide offense applied would be relevant because self-defense would not be available. A self-defense defense would not be available because (1) the person was not unlawfully present in the home (he had wife's permission) and (2) he was not committing a crime or intending to do so (he was just acting), and (3) the husband had the information that a reasonable person would have needed to learn that fact before it was too late (because his wife told him the facts clearly even though he didn't process it properly until it was too late).

  • Some interesting consequences: 1. If my friend and I commit burglary, and as a result a police officer shoots an innocent bystander, then I committed murder. If the police officer shoots my friend, then I'm innocent. 2. And this Colorado self defence law wouldn't apply if I invite someone into my home who then turns violent, right? 3. And deadly force in Colorado is allowed even if the home owner knows that deadly force is not needed?
    – gnasher729
    Jan 15, 2017 at 23:34
  • @gnasher729 1. Yes. 2. Yes (there is a separate self-defense provision at C.R.S. § 18-1-704 that would probably apply in that situation, however, which I did not cite as it did not apply in the question's fact pattern). 3. Yes. Probably a third to a half of U.S. jurisdictions have similar laws.
    – ohwilleke
    Jan 16, 2017 at 2:04

I'm having a hard time understanding what "ignoring self defense" could mean in this context. Assume the thief does not die, then what has happened? If we ignore self defense, the resident ("Smith") has battered the thief. If we don't ignore self defense, then maybe Smith is guilty of battery, or maybe not. Suppose Smith challenges the thief and cries out "Surrender! You are under arrest!", and it is obvious that the thief has stopped and surrendered – and then Smith proceeds to beat the tar out of the thief. Smith has battered the thief. Alternatively, the thief does not surrender and in fact lunges at Smith, attempting to stab him. Smith strikes the thief in self defense, and is thus privileged to use force (therefore has not battered the thief). The thing that makes a difference in these two outcomes is whether Smith's use of force is reasonable, in the context.

Let us say that the facts are that Smith had a very reasonable belief that the thief was going to kill him or his family, and while he tried to use limited force, still the guy died. Also suppose that this happens in a jurisdiction which forgot to allow for self defense. Invoking Washington law, the two issues would be whether he caused the death (he did), and whether it was with criminal negligence. We would have to ask if Smith "failed to be aware of a substantial risk that a wrongful act [death] may occur and his or her failure to be aware of such substantial risk constitutes a gross deviation from the standard of care that a reasonable person would exercise in the same situation" (emphasis added). So it kind of depends on exactly what Smith did that caused the death of the thief. If Smith swings at the thief with a maul, then that would probably be judged to grossly deviate from the standard of care... well, the problem is that "in the same situation" means "if someone is trying to kill you".

In other words, on a strict reading of the statutory law, self-defense may be actually built into the definition of "criminal negligence", so you can't exactly set it aside.


The legal concept you are looking for is "Castle Doctrine."

Under the castle doctrine you may use deadly force to defend your home. Here is a table of comparative laws:


Under the castle doctrine, deadly force is permissible under the facts you describe.


In the United States, manslaughter is a criminal act and a person can only be charged with manslaughter if their action is criminal. If a person acts in self-defense, by definition, it is lawful, so you cannot separate manslaughter from self-defense. In the United States a knife is considered a deadly weapon, so in the situation described it would be considered self-defense.

  • 3
    you can separate the prima facie elements of the crime from self-defense. States lay out the elements of the crime of manslaughter in statute, and then also provide defenses. This question asks if the scenario meets the elements of the crime, barring self-defense. This is a reasonable question as worded. Does it even meet the elements of involuntary manslaughter? Would the defendant even need to get to a self-defense argument? Or are the facts insufficient on their face to even support the charge of manslaughter? I.e. given the asserted facts, could the charge be summarily dismissed.
    – K-C
    Jan 12, 2017 at 18:44
  • @K-C thank you, that is precisely what my query was, although not as eloquently put as you have put it.
    – shirish
    Jan 12, 2017 at 23:27

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