Homicide is when one human being causes the death of another. Not all homicide is murder, as some killings are manslaughter, and some are lawful, such as when justified by an affirmative defense, like insanity or self-defense.
As the LII points out, not all homicide is murder. Manslaughter, with its legally dense and often confusing definitions, isn't murder. True self-defense, considered a legal homicide, isn't murder, either.
But all murder, by definition, is homicide.
As to those differences between murder and manslaughter — misogynistic nomenclature aside — that's a whole 'nother legal quagmire.
What Is Murder?
The legal definition of murder varies from state to state. Here's the federal definition, from the U.S. Code:
Murder is the unlawful killing of a human being with malice aforethought.
The whole idea of "malice aforethought" — which encompasses an intention to kill — has been reconsidered and refined by courts and legal scholars over the years. Currently, murder is most often broken down into categories: first-degree murder, second-degree, third-degree and so on.
All sorts of other terms can get thrown into the mix, words like malice and intent, recklessness and premeditation. Generally — again, all states are not the same — this is how it works:
First-degree murder usually, but not always, requires a willful act with premeditation, although the definition of premeditation varies, too. It generally means contemplating the act of murder — planning it in detail or simply thinking about doing it beforehand; intending to do it — and then carrying it out.
Scott Peterson, for instance, was found guilty in 2004 of first-degree murder in the death of his pregnant wife Laci who went missing on Christmas Eve from their home in Modesto, California, in 2002. Scott also was found guilty of second-degree murder in the death of their unborn child. (In October 2020, the California Supreme Court ordered the San Mateo County Superior Court to reexamine Scott's convictions because of a tainted juror pool. A new appeals trial is pending.)
Second-degree murder is first-degree murder without the premeditation or intent, but this definition, too, is dependent on where the crime is committed. According to LII, second-degree murder is typically "caused by the offender's reckless conduct that displays an obvious lack of concern for human life." It's often called "felony murder;" that is, murder committed in the act of another felony (in many cases, assault).
Third-degree murder is recognized in only a few states. One of those states is Minnesota, where former police officer Derek Chauvin faced trial in April 2021 for the 2020 killing of George Floyd. In Minnesota, "murder in the third degree" is defined as homicide without intent by acting in a way that is "eminently dangerous to others and evincing a depraved mind, without regard for human life." It can also be charged for those causing a death in drug-related cases.
Chauvin was charged with, and convicted on, three counts: second-degree murder (murder committed while he was assaulting Floyd), third-degree murder (see above), and second-degree manslaughter (see below).
Important to note: The sentences for those found guilty on murder charges, generally speaking, are more severe than those for manslaughter. The penalty for those found guilty of first-degree murder is the heaviest of all. A conviction on first-degree murder can, depending on the state (or, in the case of a federal offense), be the death penalty.
What Is Manslaughter?
Manslaughter may be considered a less serious crime than murder, with lesser sentences, but it's equally as grim; it still involves homicide.
Generally, again — yes, definitions change with manslaughter, too, depending on where the crime is committed — manslaughter is murder without intent or "malice aforethought." But it's not that simple.
Manslaughter is divided into either intentional (voluntary) or unintentional (involuntary) manslaughter. Voluntary manslaughter, according to LII, is intentionally "killing another person in the heat of passion and in response to adequate provocation." Involuntary manslaughter is "negligently" causing the death of another person.
So how can someone, then, voluntarily and intentionally kill someone — something that sounds a heck of a lot like murder — yet be charged "only" with manslaughter?
The answer: It's all in the perpetrator's state of mind.
Here's how it works in Minnesota, for an example:
First-degree manslaughter (or, in Minnesota's books, manslaughter in the first degree) occurs when voluntarily and intentionally causing a death "in the heat of passion" when provoked by words or actions that would "provoke a person of ordinary self-control under like circumstances." (A crying child is not provocation in this clause.)
Many other actions (or inactions) may prompt a charge of first-degree manslaughter rather than murder. In Minnesota, those include drug-related actions that result in a death, and punishment of a child that results in a death.
Second-degree manslaughter — we're still in Minnesota — can be charged under several different circumstances. The jury in the Chauvin case found him guilty of second-degree manslaughter because he showed "culpable negligence" when he created "an unreasonable risk, and consciously [took] chances of causing death or great bodily harm to another" by kneeling on Floyd's neck for more than nine minutes during Floyd's arrest in 2020.
Legally speaking, it gets complicated. But in homicide cases, when a person's life and liberty hang in the balance, there may be no other way to ensure that justice is served.
Now That's Interesting
Twenty-seven states currently carry a death penalty for first-degree murder, according to the National Conference of State Legislatures. Capital punishment is OK'd by the military, too, and the federal government. Since 2015, Nebraska, New Hampshire, Colorado and Virginia have abolished the death penalty. Nebraska reinstated it by statewide vote in 2016.
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