Unless the contrary is specified, every criminal offence requires both a criminal act, expressed in Latin as the actus reus, and a criminal intention, expressed as mens rea. Translated from the Latin, the expression mens rea literally means "guilty mind".
(I am reminded of a scene in that most excellent bodacious film See No Evil, Hear No Evil, with Gene Wilder and Richard Pryor as Dave and Wally, who get blamed for a murder.
Professor Kasuda advises Captain Sutherland that he's found proof Dave and Wally had the mens rea, meaning the intention to commit the murder.
Men’s rea? How could we have gotten men's rea? How is that possible? Did we take blood? Can you do it without taking blood? We both used condoms how is this possible? I want to see a doctor...I feel sick........Mens ReaOhhh ohhh My God! No!)
Mens rea is often described as the “mental element” in a crime. It can include what used to be known as “malice aforethought”, ie conscious planning or intent, as well as something culpable but less deliberate, such as recklessness or negligence.
A crime which does not require any proof of mens rea to secure a conviction is known as a one of “absolute liability” or “strict liability”. Often health codes require no mens rea, nor does the offence of driving with the prescribed concentration of alcohol in one’s bloodstream. The offence is doing it, intention to do it or awareness of doing it not being needed. (That said, even if awareness is not a defence, it can go to mitigation as far as penalty is concerned. Thus not being aware that one's drinks were spiked is not a defence but it can reduce penalty).
Which is all by way of introduction to an item I have posted before but is worthy of another airing, having come up in discussions recently with some colleagues.
It illustrates well the concepts of actus reus and mens rea.
Whilst the story below was presented by Don Harper Mills at the 1994 American Academy of Forensic Sciences dinner, the story itself is not true. It was made up by him "to illustrate how if you alter a few small facts you greatly alter the legal consequences..."
Here is Dr Mills' story:
On March 23, 1994 the medical examiner viewed the body of Ronald Opus and concluded that he died from a shotgun wound to the head. Mr. Opus had jumped from the top of a ten-story building intending to commit suicide. He left a note to the effect indicating his despondency.
As he fell past the ninth floor his life was interrupted by a shotgun blast passing through a window, which killed him instantly. Neither the shooter nor the deceased was aware that a safety net had been installed just below the eighth floor level to protect some building workers and that Ronald Opus would not have been able to complete his suicide the way he had planned.
"Ordinarily," Dr Mills continued, "Someone who sets out to commit suicide and ultimately succeeds, even though the mechanism might not be what he intended, is still defined as committing suicide." That Mr. Opus was shot on the way to certain death, but probably would not have been successful because of the safety net, caused the medical examiner to feel that he had a homicide on his hands.
In the room on the ninth floor, where the shotgun blast emanated, was occupied by an elderly man and his wife. They were arguing vigorously and he was threatening her with a shotgun. The man was so upset that when he pulled the trigger he completely missed his wife and the pellets went through the window striking Mr. Opus.
When one intends to kill subject 'A' but kills subject 'B' in the attempt, one is guilty of the murder of subject 'B'. When confronted with the murder charge the old man and his wife were both adamant and both said that they thought the shotgun was not loaded. The old man said it was a long-standing habit to threaten his wife with the unloaded shotgun. He had no intention to murder her. Therefore the killing of Mr. Opus appeared to be an accident; that is, assuming the gun had been accidentally loaded.
The continuing investigation turned up a witness who saw the old couple's son loading the shotgun about six weeks prior to the fatal accident. It transpired that the old lady had cut off her son's financial support and the son, knowing the propensity of his father to use the shotgun threateningly, loaded the gun with the expectation that his father would shoot his mother. Since the loader of the gun was aware of this, he was guilty of the murder even though he didn't actually pull the trigger. The case now becomes one of murder on the part of the son for the death of Ronald Opus.
Now comes the exquisite twist. Further investigation revealed that the son was, in fact, Ronald Opus. He had become increasingly despondent over the failure of his attempt to engineer his mother's murder. This led him to jump off the ten-story building on March 23rd, only to be killed by a shotgun blast passing through the ninth story window. The son had actually murdered himself so the medical examiner closed the case as a suicide.