State of Arizona v. Ronald Vassell, 359 P.3d 1025

Police obtained a no-knock search warrant for Vassell’s residence suspected of narcotics activity and executed it with a 10-officer SWAT team at night.
Officers breached the front door with a battering ram, repeatedly announced “Tucson Police, search warrant” (including via loudspeaker in English and Spanish), and used flash-bang distraction devices.
On entry officers saw Vassell on a couch holding a rifle; he ran into a hallway with the rifle pointed back toward officers. Two shots were later fired from the hallway/bathroom area; ballistic evidence identified a .223-caliber rifle as the source.
Police surrounding the house later secured Vassell after several hours; search recovered >14 pounds of marijuana and packaging indicia.
At trial defense requested a jury instruction on justification/self-defense (arguing Vassell may have believed intruders were home-invaders impersonating police); the court denied the instruction and convicted Vassell of conspiracy to possess marijuana for sale, possession of a deadly weapon during a felony, and endangerment.
On appeal Vassell argued the trial court erred by refusing the justification instruction; the State and majority held the evidence lacked even the "slightest" support for a reasonable belief he did not know intruders were police, while a concurring opinion would have found the evidence sufficient but concluded the claim was forfeited because the defense did not submit a written instruction under Rule 21.2.

Issue	Plaintiff's Argument (State)	Defendant's Argument (Vassell)	Held
Whether trial court erred by refusing a justification (self-defense) instruction	No — evidence showed officers clearly identified themselves and used lawful force; no slight evidence Vassell mistakenly believed they were not police	Yes — circumstantial evidence (unmarked van, darkness, flash-bangs, brief chaotic entry) permitted a reasonable inference Vassell believed entrants were home-invaders, so instruction required	Denied by majority: no slightest evidence he actually believed entrants were not police; instruction properly refused
Whether failure to submit the requested instruction in writing preserved the claim	N/A at trial; on appeal State did not raise procedural forfeiture below	Procedural default not asserted at trial; oral request sufficed because legal theory was clear and timely	Concurrence: would affirm on procedural ground — defense failed to comply with Rule 21.2 so claim forfeited; majority disagreed and addressed merits

State v. King, 225 Ariz. 87 (interpreting justification standard and directing courts to view evidence in light most favorable to party requesting instruction)
State v. Ruggiero, 211 Ariz. 262 (instruction refusal reviewed for abuse of discretion; "slightest evidence" standard for justification instruction)
State v. Hussain, 189 Ariz. 336 (same "slightest evidence" principle for defensive instruction entitlement)
State v. Walters, 155 Ariz. 548 (instruction required only if reasonably and clearly supported by evidence)
State v. Salazar, 24 Ariz. App. 472 (no instruction where no evidence defendant knew victim was not a police officer)
State v. Skinner, 118 Ariz. 517 (instruction proper where defendant denied knowledge victim was a plain-clothes officer)
State v. Johnson, 108 Ariz. 42 (trial court raised justification issue sua sponte; addressing when written submission of instruction may be excused)
United States v. Upton, 559 F.3d 3 (federal authority on timeliness and preservation for instruction requests referenced for Rule 21.2 analysis)
State v. Westlund, 536 P.2d 20 (Wash. Ct. App. — rejecting a reasonable-mistake-of-fact standard where a suspect resists lawful arrest by police)