In many legislations throughout the world, the act of intentionally killing a person had varied legal consequences, depending on the circumstances. For example, a person planning to kill their neighbor in what is supposed to look like an accident would be different than a fight escalating and leading to the death of one of the people involved.

One distinguishing factor between "murder" and "manslaughter" is whether or not there was premeditation, meaning the perpetrator made the decision to kill someone before it occurred. However, I wonder, how long before the actual killing does this decision need to be made for it to be considered "murder" as opposed to "manslaughter"?

Note: I am mostly interested in answers regarding laws in Europe, but answers regarding other jurisdictions are welcome as well.

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    In the US, the UK, and in other jurisdictions where the law ultimately derives from English common law (such as most Commonwealth countries) the presence of premeditation is the difference, not between murder and manslaughter, but between first- and second-degree murder. Commented Jun 8, 2021 at 15:09
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    @DavidSiegel I'm not aware that first and second degree murder was ever a thing in English common law. The law commission suggested it in 2004 but the proposal was rejected.
    – richardb
    Commented Jun 8, 2021 at 15:54
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    @richardb Then I may be in error as far as the UK goes. Commented Jun 8, 2021 at 15:57
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    @DavidSiegel Found this: paddyhirsch.com/murder-in-the-first-degree-a-history
    – richardb
    Commented Jun 8, 2021 at 15:57
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    @DavidSiegel: The degrees of murder are more a U.S. Thing than a UK... though the former's laws are Common Law like your commonwealth countries.
    – hszmv
    Commented Jun 8, 2021 at 16:17

2 Answers 2


It depends on the jurisdiction, but in the U.S. first degree murder will always require premeditation. The time required can be quite short too... down to nearly instantly in some jurisdictions.

Second degree Murder will typically cover Murder that is "a crime of passion" (i.e. you come home to find you spouse in bed with another man/woman and fly into a violent rage and kill the intruder.). Generally in jurisdictions that don't have instantaneous premeditation, this is used. If they do, 2nd degree includes crimes where you intend to harm the victim and got to carried away and killed them (often called Felony Murder... this could bump it to Murder in the First Degree).

Manslaughter usually implies no intent at all, but either negligence or a death that occurred as an unintended result of a lesser crime (Misdemeanor crimes generally net Manslaughter if they caused a death).

In Common Law, the intend doesn't play much of a role in the charge as it does in the sentencing. Common Law trials will first establish that a crime occurred, so intent has little to do with verdict, but with jail time (And in the U.S., depending on the state, Death Penalty. While not the only crime on the books that can get death penalty convictions, First Degree Murder is far and away the most common. The others are Treason, which is rare and difficult to prosecute, and Espionage, which is commonly plead guilty to in order to avoid the Death Penalty in exchange for telling the government the details of all they spy took.).


Intent is not needed

The definition of murder and manslaughter is actually quite short, NSW Crimes Act s18:



(a) Murder shall be taken to have been committed where the act of the accused, or thing by him or her omitted to be done, causing the death charged, was done or omitted with reckless indifference to human life, or with intent to kill or inflict grievous bodily harm upon some person, or done in an attempt to commit, or during or immediately after the commission, by the accused, or some accomplice with him or her, of a crime punishable by imprisonment for life or for 25 years.

(b) Every other punishable homicide shall be taken to be manslaughter.


(a) No act or omission which was not malicious, or for which the accused had lawful cause or excuse, shall be within this section.

(b) No punishment or forfeiture shall be incurred by any person who kills another by misfortune only.

There are 4 types of mens rea for murder:

  1. Reckless indifference
  2. Intent to kill
  3. Intent to cause GBH
  4. In the commission of a crime punishable by 25 years or life (typically another murder but also kidnapping, other crimes with aggravation etc)

Only two of these require intent.

Time is not a factor

If the prosecution is proving intent, they need to prove you had it at the time of “the act of the accused, or thing by him or her omitted to be done”.

A long and elaborately planned murder may attract a higher sentence than a “crime of passion” but they’re both murder.

  • I don't understand why this was downvoted. It seems like a perfectly sensible and well-cited answer to me.
    – MechMK1
    Commented Jun 9, 2021 at 8:00

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