Boulder, Colorado man shots person high on mushrooms who broke into his and attacked him

This seems like a very straight forward case of self defense.  From the Boulder Daily Camera:

A Boulder man will not be charged with a crime after shooting and killing a University of Colorado student who broke into his house and attacked him last week, according to the district attorney. 

Police say Roberto Zamora, 19, forced his way into 98 Pima Court at about 8:40 p.m. May 4 and attacked resident Jim McCain, whom he had never met.
McCain shot and killed him. 

Boulder County DA Stan Garnett announced Wednesday he will not charge McCain in the case, citing Colorado's "make my day" law and self-defense law. 

"Under those theories, criminal charges would not be appropriate," Garnett said. "This young man broke into the house and attacked the homeowner." . . .