Homicide: Murder and Manslaughter

Murder and manslaughter are two types of homicide—the killing of a human being.

By , Attorney · Seattle University School of Law
Updated by Stacy Barrett, Attorney · UC Law San Francisco
Updated 3/12/2024

"Homicide," "murder," and "manslaughter": What do these terms mean and how do they differ when it comes to potential criminal charges and penalties?

The term homicide means the killing of another person—but it's not necessarily a crime. Certain homicides are lawful (such as in wartime), while others are unlawful (such as murder and manslaughter). Here's an overview of the range of crimes falling under the umbrella of homicide, including their elements and penalties.

What Is Homicide?

When we hear the term "homicide," we tend to think of murder and manslaughter. But these are just two types of homicides. The term homicide covers lawful killing (such as a killing in self-defense), intentional killing (murder), state-sanctioned killing during war, and negligent or reckless killing (manslaughter). Homicide even describes what happens when the government executes someone.

What Is Murder?

Murder is one type of homicide under the law. The crime of murder is the killing of one human being by another that is:

  • intentional (an accidental killing is usually not murder, except in cases of felony murder)
  • unlawful (as opposed to the lawful killing by a police officer of a suspect during a shoot-out, for example), and
  • done with "malice aforethought."

What Is Malice Aforethought?

It sounds like something out of a Shakespeare play, but malice aforethought is a legal term that describes a state of mind or action that shows an:

  • intent to kill
  • intent to inflict very serious or grievous bodily harm
  • reckless indifference to the value of human life, or
  • intent to commit a dangerous felony that results in the death of another.

What Are the Different Degrees of Murder?

Although laws on murder vary from state to state, most states recognize different degrees of murder—premeditated murder (first-degree murder), unpremeditated murder where the defendant intended to inflict serious bodily harm (second-degree murder), and felony murder (death caused during the commission of a dangerous felony).

Here are some examples of these common types of murder.

First-Degree Murder

First-degree murder is typically a deliberate, premeditated killing. In 2013, Jodi Arias was convicted of first-degree murder in a sensational trial that was widely covered in the media and is the subject of many documentaries and books. Prosecutors argued that she plotted the murder of her ex-boyfriend, Travis Alexander, for days or weeks. She stole a gun from her grandparents' home to use as one of the murder weapons and she tried to conceal her identity and whereabouts by removing her license plate and turning off her phone, indicating premeditation. Arias tried to argue the killing was in self-defense, after initially denying she was at the scene, but the jury didn't believe her. Arias was sentenced to life in prison without the possibility of parole.

Second-Degree Murder

Second-degree murder is an intentional killing that wasn't premeditated. For example, former NBA player, Keith Appling, was convicted of second-degree murder in Michigan in 2023. He pled guilty to killing a relative during a fight over a gun. The murder was impulsive, but Appling acted with intent and understanding when he pulled the trigger multiple times.

Felony Murder

Most states have some version of "felony murder" on the books. This controversial law allows prosecutors to charge defendants with murder if a death occurs because of a felony they committed, even if they weren't the direct killer. For example, a Florida woman, Jennifer Mee, was convicted of felony murder in 2013. She had arranged for her two male roommates to meet Shannon Griffin to sell him marijuana. Instead, the two men tried to rob Griffin and shot him to death. Mee didn't pull the trigger and wasn't even accused of being at the scene, but she was convicted of felony murder because she set the drug deal that led to Griffin's death in motion.

In some cases, a defendant may even be charged with felony murder for the death of an accomplice. For example, 15-year-old Justin Doyle broke into a house in Illinois with two friends in 2008. The teenagers were unarmed and expected the house to be empty, but it wasn't. A housesitter was startled awake during the break-in and shot Doyle's 14-year-old friend. Doyle was charged as an adult with felony murder for his friend's death. Facing a potential sentence of between 20 and 60 years with no possible time reduction, Doyle eventually accepted a plea to lesser charges for a 15-year sentence.

What Is Manslaughter?

Manslaughter (another type of homicide) is the unlawful killing of one human being by another without malice aforethought. Again, laws vary from state to state, but most states recognize a few types of manslaughter.

Voluntary Manslaughter

Voluntary manslaughter is an intentional killing, but the killing is provoked and happens in the "heat of passion." The classic example of voluntary manslaughter is a husband who unexpectedly comes home to find his wife in bed with another man and then kills her lover in a fit of rage. The killing is intentional, but the emotional context reduces the husband's culpability (blameworthiness).

Another common voluntary manslaughter example is what's called "imperfect self-defense." The law allows people to use deadly force to defend themselves from an immediate threat of harm (more on that below). The amount of force used must be proportional to the threat. When a person honestly believes they were in immediate danger, but their belief or the amount of force they used was unreasonable, they may be charged with or convicted of voluntary manslaughter instead of murder.

Involuntary Manslaughter

Involuntary manslaughter is an unintentional killing that results from criminally negligent or reckless conduct. In some states, it can also refer to an unintentional killing that happens during the commission of a misdemeanor or non-dangerous felony (similar to a felony murder).

In early 2024, Hannah Gutierrez-Reed was convicted of involuntary manslaughter in connection with a fatal shooting on the set of the movie "Rust." Guitierrez-Reed was the armorer who put a live round in the gun that the actor Alec Baldwin was rehearsing with when it went off, killing the cinematographer on set. The jury found that Guitierrez-Reed willfully disregarded the safety of others when she carelessly handled weapons and ammunition and failed to carry out gun safety checks. She was sentenced to the maximum possible prison term of 18 months. Baldwin has also been charged with involuntary manslaughter for his role in the fatal shooting. His trial is set to begin on July 9, 2024.

Vehicular Manslaughter

Most states have "vehicular manslaughter" laws that apply exclusively to drivers who kill someone while operating a vehicle. Depending on the state, vehicular manslaughter may include causing the death of another person while:

  • operating a vehicle in a negligent, grossly negligent, or reckless manner
  • driving in violation of the state's DUI laws, or
  • committing certain traffic offenses.

Vehicular manslaughter can be charged as a misdemeanor or felony based on the degree of negligence involved. Was the driver going a few miles over the speed limit in a residential neighborhood or 80 mph in a 40 mph zone?

Three Common Defenses to Murder

Murder is one of the most severe charges a person can face with some the heaviest penalties. But proving murder can be difficult. Here are some common defenses that criminal defendants raise in murder cases.

Justifiable Killing or Self-Defense

In the trial over the killing of Trayvon Martin in 2013, George Zimmerman succeeded in arguing that he acted in self-defense. Zimmerman, a neighborhood watch volunteer, saw Martin walking in the rain in February 2012. Martin was carrying Skittles and a drink. Zimmerman called the police and reported Martin as a "suspicious person." The 911 dispatcher told Zimmerman not to follow the person. Still, he got out of his car and into a physical altercation with Martin that ended with Zimmerman fatally shooting Martin. Zimmerman managed to persuade the jury that he was defending himself against a life-threatening attack by Trayvon Martin and was acquitted.

For more on self-defense and the Zimmerman case, check out "Stand Your Ground": New Trends in Self-Defense Law.

Heat of Passion

As noted above, defendants who lash out in the heat of passion may be charged with voluntary manslaughter instead of murder or may avoid charges altogether. In 2012, for example, a 23-year-old Texas man heard his daughter crying behind a barn. He ran to her and found a man molesting her. He immediately pummeled the man to death with his hands. A grand jury declined to bring charges against the father, finding that he was justified in using deadly force to protect his daughter. Several community members told reporters that they believed the man just did what any parent would do under the circumstances.

Insanity, Impairment, and Infancy

Certain defenses are based on the defendant's mental state. For example, insanity, intoxication, and even a defendant's young age may be raised as a defense to murder charges.

Mental Disorders

A defendant's mental disorder may be an affirmative defense to an intentional crime such as murder. Standards vary from state to state, but defendants who raise this defense typically have to prove that they couldn't appreciate the nature or wrongfulness of their actions at the time of the crime. Defendants who are found not guilty because of insanity typically aren't released into the community but are committed to mental institutions instead of prison.


A person with an impaired mental state, such as intoxication, might be able to argue that their impairment prevented them from forming the intent necessary to commit a crime like murder. If a defense like this is successful, it may lead to a conviction on a lesser charge, like manslaughter, instead of murder. The fact that the person was too intoxicated to intend to kill or even seriously injure another isn't a defense to manslaughter because manslaughter doesn't require proof of intent to kill.


Prosecutors may also consider the age of defendants when deciding whether and which charges to bring. About half of the states in the United States have a minimum age for prosecution because children and adolescents are generally understood to lack a full appreciation of the consequences of their actions. In 2023, a 6-year-old boy shot his elementary school teacher in Virginia. The teacher was seriously wounded in her hand and chest. Even though Virginia has no minimum age for prosecution, the city prosecutor decided not to seek charges against the child. The police described the shooting as "intentional" but the child simply wasn't old enough to understand the legal system and assist with his defense. The boy's mother, Deja Taylor, pled guilty to child neglect and federal gun charges in connection with the incident.

Penalties for Murder

The precise punishment for murder varies from state to state. Most states impose a sentence of life in prison for first-degree murder, with or without the possibility of parole. Second-degree murder almost always carries a lesser penalty than first-degree murder but the maximum punishment is typically still decades in prison.

In about half of the states, aggravated first-degree murder is punishable by the death penalty.

Penalties for Manslaughter

The punishment for manslaughter is generally less than for any degree of murder, although penalties vary from state to state. Maximum prison sentences tend to range anywhere from a few years to 10 or 15 years. An individual convicted of involuntary manslaughter might not receive a prison sentence under certain circumstances, while one convicted of voluntary manslaughter likely would.

Talk to an Attorney

Murder and manslaughter are very serious and complex crimes. If you believe you are being investigated for murder or manslaughter or you've been arrested or charged, talk to a criminal defense attorney as soon as possible. A lawyer can answer your questions about the law, investigate the facts, and protect your rights.

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