You said castle doctrine which always means in regards to ones home.

As far as on the street out in public there is nothing in any law that says you have a duty to retreat. The only thing it says is that you can not esculate the situation or be the one who provoked it.

Here is the statue pay attention to section 3 a, b and c.


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.

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 grounds 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 184-204; 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 184-301 or 184-302, sexual assault as set forth in section 18-3-402 or 18-3-403, or assault as defined in sections 18-3-202 or 18-3-203.

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.

There are also other laws that address property ect. Here is a link to the county sheriffs of colorado web site it lists all the statues. The statues are at the bottom of the page.

http://www.csoc.org/ccw_application_template.html