When dealing with the difference between “manslaughter” and “murder” it depends on the state of mind of the killer as well as the various degrees relating to murder.

Definition of Murder

In California murder is defined as killing somebody with “malice aforethought,” which is malice. The two types of malice is “express malice” and “implied malice.” Express malice is when a person intended to kill another person or persons. Implied malice is when a person intentionally commits an act they knew was dangerous to other people and human life resulting in death. In other words, the murder was committed with a conscious disregard for human life.

If a crime involves expressed or implied malice its defined as “murder.” Murder is further classified into first degree and second degree. First degree murder is one that is willfully and deliberately committed with premeditation, meaning the person willfully decided to kill the other person. A second degree murder is when a person intentionally meant to kill another person but it was not planned or premeditated, such as in a “heat of passion” or the killing was the result of a person’s dangerous conduct involving a conscious disregard for human life.

Definition of Manslaughter

Manslaughter is also the unlawful killing of another person or persons, but without any malice but still involves a “conscious disregard for human life.” Manslaughter can be voluntary or involuntary. Voluntary manslaughter is when the act of murder is committed in either the heat of passion or in the defense of yourself or others. Involuntary manslaughter is when a killing is unintentional and the result of recklessness or criminal negligence, such as an unlawful misdemeanor act or low-level felony such as a DUI.

A “heat of passion” is defined as a killing resulting from a person being provoked, a rash act from intense emotion from being provoked, or the person was provoke in such a way that an average person would normally act rashly.

Basically, a jury must decide the person was provoked to the point where he was acting under intense emotion instead of pre-meditated anger.

Manslaughter is an unlawful killing that doesn’t involve malice aforethought—intent to seriously harm or kill, or extreme, reckless disregard for life. The absence of malice aforethought means that manslaughter involves less moral blame than either first or second degree murder. (But plenty argue that some instances of felony murder, a form of first degree murder, involve less blameworthiness than some instances of manslaughter.) Thus, while manslaughter is a serious crime, the punishment for it is generally less than that for murder.

Voluntary Manslaughter

This is often called a “heat of passion” crime. Voluntary manslaughter occurs when a person:

  • is strongly provoked (under circumstances that could similarly provoke a reasonable person) and
  • kills in the heat of passion aroused by that provocation.

For “heat of passion” to exist, the person must not have had sufficient time to “cool off” from the provocation. That the killing isn’t considered first or second degree murder is a concession to human weakness. Killers who act in the heat of passion may kill intentionally, but the emotional context is a mitigating factor that reduces their moral blameworthiness.

The classic example of voluntary manslaughter involves a husband who comes home unexpectedly to find his wife committing adultery. If the sight of the affair provokes the husband into such a heat of passion that he kills the paramour right then and there, a judge or jury might very well consider the killing to be voluntary manslaughter.

Involuntary Manslaughter

Involuntary manslaughter often refers to unintentional homicide from criminally negligent or reckless conduct. It can also refer to an unintentional killing through commission of a crime other than a felony.

The subtleties between murder and manslaughter reach their peak with involuntary manslaughter, particularly because an accidental killing through extreme recklessness can constitute second degree murder.