There has been a recent incident relating to a person with diplomatic immunity (a US citizen) being involved in a fatal car crash in the UK. My question is born out of reading about this case, but I'm looking for a general answer; what should happen in every case, not what will happen in this case.

From what I've read a person is only able to receive diplomatic immunity if they are in the foreign nation, and therefore any immunity ends when the person returns home. Does that mean once the person has returned home they can then be held accountable for their actions while in a foreign nation? If so who exactly can hold the person accountable? If the crime wasn't committed in the home nation then their government presumably has no jurisdiction and/or no way to investigate the crime. But if the foreign nation is able to pursue the individual once they have returned home it feels like it short-circuits the entire principal of diplomatic immunity.

  • Great question. I was also wondering why it matters if Anne Sacoolas lost her immunity, given that she had immunity at the time of the crash. Commented Oct 15, 2019 at 18:18
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    @divibisan that seems more like a waiver being requested and granted. If they are held accountable for the crime in the forgien nation it seems like that requires the home nation to grant the waiver of the immunity. Commented Oct 15, 2019 at 18:42
  • @user6916458 but the extradition request would be processed (usually) by a judge while the waiver of immunity would be a decision of the Executive. Also, if there is no extradition treaty then the request would be simply ignored.
    – SJuan76
    Commented Oct 15, 2019 at 20:42

1 Answer 1


If a diplomat commits a crime, and immunity is not waived, then the diplomat will typically be instructed to leave the country (declared "persona non grata"). Once they return home it is a matter for the home country. There are no diplomatic rules for how the home country treats expelled diplomats. Normally they would face no criminal charges of any kind.

The foreign country would have no reasonable right to extradite, even if a comprehensive extradition treaty existed, as there is no way to prosecute a person for the crime.

Immunity ends when they return home, so any further crimes they commit after returning home can be prosecuted. This doesn't affect immunity for crimes committed as a diplomat. They can't be prosecuted in the foreign country, and it is vanishingly unlikely that they would be prosecuted in the home country.

A possible exception to this is when a country has a specific crime which relates to offences committed abroad. For example, some countries have crimes that make child sexual abuse illegal, even when committed abroad (and even when not a crime in the foreign country). It is at least conceivable that the immunity that a diplomat holds from prosecution in a foreign country would not prevent prosecution in their home country on a charge of child sexual abuse, if such a crime existed. As far as I am aware, this has never been tested.

The twist in the Harry Dunn case is that the US diplomat was not required to leave, but did so of her own volition. The usual diplomatic process of declaring a person "persona non grata" wasn't followed, so (the Foreign Office argues) she lost the right to claim immunity and can be extradited.

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    It might be clearer to speak about sending states and receiving states. Home and foreign are rather ambiguous.
    – JJJ
    Commented Oct 16, 2019 at 0:54
  • Note on the last paragraph: Some countries (AFAIK, not the US though) forbid the extradition of their own citizens. -- Apart from that I do not understand the sequence of events: Normal: 1) receiveing state tries to arrest/accuse 2) diplomat claims immunity 3) diplomat declared persona non grata 4) diplomat leaves. So in contrast, here step 4 happened before steps 2 and 3 - but after step 1? Commented Oct 16, 2019 at 6:04
  • I believe she was being interviewed by the police rather than charged with a crime and said she wasn't going to leave the country - but then did. Commented Oct 16, 2019 at 13:36
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    There is also the option of a nation recalling it's own diplomat, which means that before they are expelled, the sending nation sees that it's a good idea to pull them back. This is more likely to face some kind of reprimand. In one famous case, a Saudi Diplomat (also the King's son) was recalled and executed for his crime (and embarrassing his dad), which I don't think the Host nation considered an executable offense. Sending nations may also revoke immunity, which means that they aren't going to even bring you back home... you can be arrested and dealt with with out extradition.
    – hszmv
    Commented Oct 16, 2019 at 13:53
  • This answer is correct only if the crime was committed as an official act. Otherwise, the diplomat may be prosecuted after the termination of the immunity.
    – phoog
    Commented Aug 9, 2022 at 18:01

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