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18-1-704. Use of physical force in defense of a person



(1) Except as provided in subsections (2) and (3) of this section, a person is justified in using physical force upon another person in order to defend himself or a third person from what he reasonably believes to be the use or imminent use of unlawful physical force by that other person, and he may use a degree of force which he reasonably believes to be necessary for that purpose.

You may protect yourself and/or others from attack by another PERSON, but you may only use a reasonable level of force. We highlight person here because attack by animals doesn't allow you to invoke self defense as a justification for discharging a firearm.

(2) Deadly physical force may be used only if a person reasonably believes a lesser degree of force is inadequate and:

(a) The actor has reasonable ground to believe, and does believe, that he or another person is in imminent danger of being killed or of receiving great bodily injury; or

(b) The other person is using or reasonably appears about to use physical force against an occupant of a dwelling or business establishment while committing or attempting to commit burglary as defined in sections 18-4-202 to 18-4-204; or

(c) The other person is committing or reasonably appears about to commit kidnapping as defined in section 18-3-301 or 18-3-302, robbery as defined in section 18-4-301 or 18-4-302, sexual assault as set forth in section 18-3-402, or in section 18-3-403 as it existed prior to July 1, 2000, or assault as defined in sections 18-3-202 and 18-3-203.

You can only use deadly force is a narrow set of circumstances. Colorado defines deadly force as force applied which results in death. Shooting an assailant is not considered a use of deadly force unless the assailant does indeed die.

(3) Notwithstanding the provisions of subsection (1) of this section, a person is not justified in using physical force if:

(a) With intent to cause bodily injury or death to another person, he provokes the use of unlawful physical force by that other person; or

(b) He is the initial aggressor; except that his use of physical force upon another person under the circumstances is justifiable if he withdraws from the encounter and effectively communicates to the other person his intent to do so, but the latter nevertheless continues or threatens the use of unlawful physical force; or

(c) The physical force involved is the product of a combat by agreement not specifically authorized by law.

You can't use deadly force if you picked the fight unless you quit fighting and the other person continues to attack.

(4) In a case in which the defendant is not entitled to a jury instruction regarding self-defense as an affirmative defense, the court shall allow the defendant to present evidence, when relevant, that he or she was acting in self-defense. If the defendant presents evidence of self-defense, the court shall instruct the jury with a self-defense law instruction. The court shall instruct the jury that it may consider the evidence of self-defense in determining whether the defendant acted recklessly, with extreme indifference, or in a criminally negligent manner. However, the self-defense law instruction shall not be an affirmative defense instruction and the prosecuting attorney shall not have the burden of disproving self-defense. This section shall not apply to strict liability crimes.

18-1-704.5. Use of deadly physical force against an intruder (aka Castle Doctrine)

(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.

So, you have immunity if all of the following are true:

  • The person made unlawful entry into the dwelling (note the legal definition of dwelling section 18-1-901)
  • You have a reasonable belief that the person committed (or intends to commit) a crime in the dwelling other than the unlawful entry.
  • You have a reasonable belief that the person will use any level of physical force against any occupant of the dwelling


(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.

You are protected, by law, from criminal prosecution if it found that your use of force is covered under 18-1-704(2)

(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.

You are protected, by law, from civil liability if it found that your use of force is covered under 18-1-704(2) A finding of immunity from criminal prosecution is NOT an automatic guarantee of civil immunity. You'll have to prove, in civil court, that you are immune under 18-1-705(2)

(5) As used in this section, unless the context otherwise requires, "dwelling" does not include any place of habitation in a detention facility, as defined in section 18-8-211 (4).

Prisoners may not use this as a defense

18-1-705. Use of physical force in defense of premises

A person in possession or control of any building, realty, or other premises, or a person who is licensed or privileged to be thereon, is justified in using reasonable and appropriate physical force upon another person when and to the extent that it is reasonably necessary to prevent or terminate what he reasonably believes to be the commission or attempted commission of an unlawful trespass by the other person in or upon the building, realty, or premises. However, he may use deadly force only in defense of himself or another as described in section 18-1-704, or when he reasonably believes it necessary to prevent what he reasonably believes to be an attempt by the trespasser to commit first degree arson.

You may use deadly force to stop 1st degree arson, but only when it's being committed by a trespasser. If an angry spouse tried to kill his/her family by burning the house down...technically the angry spouse isn't a trespasser (absent some form of protection order, etc.).