Court Continues to Prohibit Expert Psychiatric Evidence of Mental Illness During Guilt Phase

State v. Peterson, Minn.S.Ct., 5/7/2009.  Mr. Peterson apparently shot and killed Howard Hines as Mr. Hines sat in the driver's seat of his car; Mr. Peterson shot from his third floor apartment window.  Mr. Peterson pleaded not guilty by reason of insanity and waived a jury trial.  He asked to be allowed to present expert psychiatric evidence during the guilt phase of his trial on the question of his mental state; the trial court said, no.  The court found Mr. Peterson guilty.  The court also rejected Mr. Peterson's mental illness defense during the sentencing phase of the trial.

On appeal, Mr. Peterson said that denying expert psychiatric testimony during the guilt phase violated his due process right to present a complete defense.  As the appellate court has said many times, it again said, no, it doesn't.  See State v. Brom, 463 N.W.2d 758 (Minn. 1990).  The appellate court recognized the two broad exceptions to this prohibition, established in State v. Provost, 490 N.W.2d 93 (Minn. 1992):

(1) the rare situation where there is a mental disorder characterized by the formation of a particular subjective state of mind inconsistent with the pertinent criminal mens rea; or (2) where the defendant has a past history of mental illness and the evidence is in the nature of factual background to explain “the whole man,” such as a clinical record where psychiatric opinions appear.

The appellate court concludes that Mr. Peterson did not satisfy either of these exceptions.  The appellate court then upholds the trial court's rejection of Mr. Peterson's mental health defense.

Finally, the appellate court does decide that the trial court's sentence of life without possibility of release was error.  This was because at the time of the murder, Minn.Stat. 609.185 did not authorize life without possibility of release.  Mr. Peterson beat the effective date of an amendment that authorized that sentence by some six months.  The appellate court modifies the sentence to life with the possibility of supervised release after thirty years.