It is difficult in any state for mothers like Mine A. Ener, charged in St. Paul with murdering her 6-month-old daughter, to use postpartum depression as the basis for an insanity defense, the Minneapolis Star Tribune reports. But nowhere is an insanity defense more difficult to win than in Minnesota, which uses a 19th-century British standard known as the M’Naghten rule. It says only people who do not know right from wrong or who do not understand the nature of their acts can be found not guilty by reason of mental illness.
That means it would be almost impossible to use postpartum depression as a defense in Minnesota unless the depression caused severe psychotic reactions such as delusional beliefs, said Prof. Eric Janus of William Mitchell College of Law in St. Paul. Because M’Naghten sets standards only for what a person understood, it does not take into consideration illnesses like postpartum depression, which is considered an impairment of mood, Janus said.
A criminal complaint says Ener told police she killed her daughter, Raya Donagi, because the girl had Down syndrome, Ener felt the infant’s situation was hopeless and she did not want her to go through life suffering. Ener also said she had been contemplating suicide for the past two to three weeks.
The Minnesota Supreme Court adopted the M’Naghten rule in 1868. Since then, modern psychology and psychiatry came into being, and their practitioners often take the witness stand in courtrooms to offer expert testimony. But the M’Naghten rule, the product of an 1843 British murder case, is still the law in Minnesota. Experts agree it is the most difficult of several insanity standards used across the country. About half the states permit a finding of not guilty for people who commit crimes because of an “irresistible impulse” — those who could not stop themselves from committing a crime due to mental illness even when they knew it was wrong.