Thompson v. State, 436 P.3d 642

In 2011 Thompson shot and killed Michael Blair in a pickup after Blair put his mouth on the barrel of a loaded gun; Thompson claimed Blair fired the gun himself. Thompson was convicted of involuntary manslaughter with a deadly-weapon enhancement and sentenced to 15 years (5 fixed).
Trial counsel did not request jury instructions specifically on proximate cause or intervening/superseding cause; the jury was instructed using statutory language that the defendant’s use of a firearm "produced" the death and that the State must prove the defendant "unlawfully caused" the death.
Thompson’s direct appeal was unsuccessful. He then filed a post-conviction petition alleging ineffective assistance of trial counsel (failure to request proximate/intervening-cause instructions) and ineffective assistance of appellate counsel (failure to raise a fundamental‑error instruction claim).
The district court granted the State’s motion for summary dismissal, concluding the statutory/ICJI-form instructions adequately covered causation and an additional proximate/intervening‑cause instruction would not have changed the outcome.
The Court of Appeals reversed; the Idaho Supreme Court granted review and affirmed the district court, holding Thompson did not meet Strickland prejudice or deficiency standards for either claim.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Trial counsel ineffective for failing to request proximate‑cause instruction	Thompson: "produces" in statute requires proximate‑cause instruction; omission was deficient and prejudicial	State: statutory language and ICJI already instructed causation; additional instruction unnecessary and would not change verdict	Court: Not ineffective — instructions tracked statute/ICJI; no reversible error; no reasonable probability of different outcome
Trial counsel ineffective for failing to request intervening/superseding‑cause instruction	Thompson: intervening‑cause instruction could have shown Blair’s act broke causal chain	State: no evidence of unforeseeable, extraordinary intervening act; instruction not required and would not change result	Court: Not ineffective — no basis that an intervening cause would relieve criminal liability here; omission not prejudicial
Appellate counsel ineffective for not raising fundamental‑error (instructional) claim	Thompson: appellate counsel should have argued fundamental error in jury instructions on causation	State: appellate counsel may decline weaker issues; no reasonable probability of success on an instructional claim	Court: Not ineffective — because trial counsel was not ineffective and the instructional claim lacked merit, appellate omission was not objectively unreasonable

Strickland v. Washington, 466 U.S. 668 (establishes two‑prong ineffective‑assistance test)
State v. McKay, 148 Idaho 567 (trial counsel ineffective where jury instructions omitted statutory elements)
State v. Lampien, 148 Idaho 367 (definition and standards for intervening/superseding cause)
State v. Abdullah, 158 Idaho 386 (discusses when causation instructions may be required under arson statute)
Crawford v. State, 160 Idaho 586 (Strickland analysis focuses on whether instructions were reversible error)
State v. Monteith, 53 Idaho 30 (vehicular manslaughter case where proximate cause was submitted to jury)