Given all the recent talk of how President Trump's travel ban will affect dual citizenship holders, a few questions were raised.

Now I know how dual citizenship works, on obtaining it and how each country holds their own laws on what qualifies. What I really want to know: Is there any international law governing the processes, what and how would this be enforced, and can somebody have triple citizenship (or more) under certain circumstances?

Say for example an Israel-born United States citizen were to perform an extreme act of bravery in the UK, and be knighted (I'm unsure of the process, but if that's not possible than the foreigner equivalent). Could that person gain citizenship in the UK, without denouncing either their Israeli or American citizenship?


6 Answers 6


Citizenship is Boolean

Under the Master Nationality Rule citizenship is effectively a boolean value: you are either a citizen of a country or not. From any single-country's perspective, you are either their citizen or not. A hypothetical dual citizen (say, US and Canadian) would be fully subject to US expectations and rights (jury duty, military service, etc.) while in the United States, but also subject to the same responsibilities in Canada while in Canada.

At face value, this isn't particularly important, but it is important for explaining why you aren't finding more information. Domestic laws don't care if you are a dual-citizen, tri-citizen, poly-citizen, or whatever - they only care that you are (or are not) a citizen at all.

It's Unlikely

A second reason you aren't finding much information is because it is an unlikely situation. Law is not a theoretical science, it tends to address issues that have arisen in the past and been resolved (or have failed to resolve) through the legal process.

Until there are people trying to claim n-citizeship status, there is unlikely to be a rule that covers it.

A Hypothetical Situation

Still, as a thought experiment we could construct a situation where triple citizenship would be possible.

For example, if:

  • My mother was a citizen of Canada
  • My father was citizen of Mexico
  • I was born in the United States and neither of my parents was a diplomat

Then I likely qualify for three citizenships: Canadian, Mexican, and US.


  • Being born abroad to a Canadian citizen (by blood) may qualify me to be a Canadian citizen. (Source: Canada's immigration website)
  • Being born abroad to a Mexican citizen (by blood) may qualify me to be a Mexican citizen. (Source: Wikipedia, because I can't read Spanish).
  • Being born in the United States may qualify me to be a US citizen (Source: Immigration and Nationality Act).

In general though, you would have to read through the citizenship laws of each individual country to reach any kind of conclusion.

  • Comments are not for extended discussion; this conversation has been moved to chat. Feb 3, 2017 at 22:11
  • As a FYI, I looked into the conditions of Canadian citizenship myself since I'm a citizen through my mother, and the site you reference says this: "You are not automatically a Canadian citizen if… you are born outside Canada to Canadian parent(s) on or after April 17, 2009, but neither parent was born or naturalized in Canada." So, while I'm a citizen since I meet both conditions, my children do not. It doesn't make your example wrong, but it has some additional conditions to consider.
    – Ellesedil
    Feb 15, 2017 at 0:27
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    The child citizenship act of 2000 does not apply to children born in the United States. Their citizenship is derived from the fourteenth amendment, and it does not depend on the nationality of the parents..
    – phoog
    Feb 15, 2017 at 16:24
  • @phoog - I corrected this by removing the reference to the Child Citizenship Act, replacing it with INA. I used INA instead of Amendment XIV because that's what Immigration referenced. I figure they know their stuff. Feb 20, 2017 at 20:44
  • Well the INA implements (and uses the language of) the 14th amendment, which of course supersedes it, but that's a minor distinction. It's still incorrect to say "to at least one US citizen," though, since the parents' citizenship is irrelevant except in the case of a child born to a diplomat.
    – phoog
    Feb 21, 2017 at 2:16

There isn't much international law on this (and to the extent that there is, e.g. things like the Strasbourg Convention on the Reduction of Cases of Multiple Nationality and on Military Obligations in Cases of Multiple Nationality, it only covers few cases) so you won't find any generic process or overarching rules.

As you wrote yourself, it comes down to the rules in each country and I am not aware of any country that makes a difference between dual and “plural” citizenship. Many countries impose some restrictions (like an obligation to renounce other citizenships in some circumstances) but when they do not there is no need for any rule specifically allowing three or more citizenships.

With that in mind, three citizenships is quite common, I personally know several people in this situation, including several members of my family. Getting to four or five is not particularly difficult, even without far-fetched scenarios like being knighted, e.g. children born just about anywhere in the Americas to parents who hold two citizenship from any of the many countries which allow transmission of the citizenship by descent would automatically hold five citizenships.

If you don't count citizenship by birth and think about someone who starts with only one as an adult, getting multiple citizenship requires more work (because it is often necessary to reside for few years and learn the language before becoming a citizen) but is entirely possible. You would need to acquire citizenships from countries that don't require you to renounce previous citizenship for naturalisation (that includes your three example countries: the UK, the US, and Israel…) Marrying or even in some cases investing in the country can make things easier and quicker.

  • There are several small Caribbean countries that apparently let you buy a citizenship. With two or three million dollars you should be able to collect them all. (Google for St. Kitts citizenship, for example).
    – gnasher729
    Feb 15, 2017 at 20:56
  • @gnasher729 Malta does too, more-or-less (you have to buy a house and pretend to stay there for a year to save appearances so you can't just wire the money and become a citizen in a week but you can still basically buy it). And that's probably a more valuable citizenship (gets you freedom of movement in the EU for example).
    – Relaxed
    Feb 16, 2017 at 8:30
  • I appreciate the anecdotal support in this answer. Il be back in 24 hours to administer the bounty. Feb 16, 2017 at 14:31

Having dual citizenship simply means, well, you have two citizenships. If you are both a US and a Canadian citizen, you are simply entitled the rights of both American and Canadian citizens, and held to the duties of both. Nothing prevents you from having more citizenships - if one born to Japanese and Canadian parents in the US, one has Japanese, Canadian and American citizenships (technically only before 22 though - Japan does not recognize multiple citizenship for adults and requires a selection before one attains 22 years).

However, citizenship is essentially regulated by domestic law, where international treaties are only a secondary regulatory factor. Even if the hypothetical person described above declare that he/she gives up American and Canadian citizenships to Japanese authorities, American and Canadian authorities could not have and will not acknowledge this declaration. As far as American and Canadian authorities are concerned, that person is still a citizen. He/she may still renew his/her US passport and vote for president if he/she wishes.

In this case, it is just that Japanese authorities consider him/her a Japanese citizen only and will treat him/her as a citizen. For example, Japanese authorities will not be obliged by the Article 36 of the Vienna Convention on Consular Relations to report to US consular officers had the person been arrested in Japan - because that person is not a US citizen as far as Japanese authorities are concerned. Otherwise, if he/she manages to never get arrested and present only to Japanese border control his/her Japanese passport, there is really no reason he/she will get into any trouble. A state's non-recognization of multiple citizenship only concerns itself, and have no impact on the government of foreign states.

PS: I have heard of stories where Chinese citizens naturalized in Portugal have their Chinese passport confiscated by Portuguese authorities (due to their naturalization) and then report to Chinese authorities that their passports are "lost" so that they get new Chinese passports. Portugal accepts multiple nationality, but in recognition of China's non-acceptance, they do confiscate Chinese passports should a Chinese citizen naturalize. Portuguese authorities acknowledge that the person have forfeited his/her Chinese citizenship, but Chinese authorities do not (because they did not register the forfeiture of their Chinese citizenship with Chinese authorities) so the Chinese embassy still considers him/her a Chinese citizen.

Note that this is not legal - failing to report naturalization to Chinese authorities is misrepresenting facts to authorities and will result to the least the stripping of one's Chinese nationality. However, this will happen only if they actually find out - the Portuguese government has no obligation to report naturalizations to Chinese authorities.

  • That is strange. I would have thought that your Chinese citizenship (or any non-Portuguese citizenship) would be of no consequence to authorities in Portugal whatsoever.
    – gnasher729
    Feb 20, 2017 at 11:47
  • @gnasher729 It does not. Portuguese authorities take Chinese passports only in acknolwedgement of Chinese non-recognition of multiple citizenships. Beside this, they don't care.
    – xuq01
    Feb 20, 2017 at 20:42

I have 3 citizenships: my country of birth, my father's country of birth, my spouse's country of birth (Canada, UK, USA, respectively).

There is nothing anywhere that officially acknowledges this situation. I have 3 passports that are independent of each other.


There is no international law governing citizenship. There is, however, a stateless person and it is recognized by international laws and there is a United Nations High Commissioner for Refugees. For UN refugee is a stateless person quite often. Look it up and have a read.

As for your question: citizenship is regulated internally. You can obtain it in various ways, and every time it might be different - from slightly to wildly.

For example, I'm Polish citizen born in Poland. But my parents are eligible for German passport and additionally my daughter will be eligible for British passport sometime in the next year or so. However, for a long time multiple citizenship was expressly forbidden in Poland (and in many Eastern Bloc countries as well), until joining the EU, when it was changed - EU carries with the accession EU citizenship for everyone in it... So If I wanted to have multiple passports I would have to renounce Polish one.

There is also a... twist in the plot, let's say. Obviously once you have the citizenship of several states you are obviously first and foremost citizen of the one you are in right now (of those you belong to). This means you have to use documents required by the local law and fulfill all the duties as long as you're there. Which sometimes is comical: for example, in Poland you need to use polish documents and if any one of those is invalid (past valid date) it's not possible to use it and in extreme cases you might be denied entry to Poland - even if you have another country's passport with you which is valid. By the same token you cannot switch between them as you like (i.e. present polish passport on the border but then using UK driving licence might just buy you a heap of trouble...

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    I don't see why using Polish passport and UK driving licence can get you in trouble. It is quite common situation now when there are many Polish expats in the UK. Oct 5, 2022 at 7:29
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    @PiotrGolacki indeed, and driving licenses are (more or less) based on residence, not citizenship, so it's common in all sorts of cases for licenses and passports to be issued by different countries. The only problem would likely be trying to use a foreign license if you actually reside in Poland.
    – phoog
    Oct 7, 2022 at 23:50

There's no such concept as "international law", but obviously several agreements have been made to standardize aspects of citizenship in the majority of countries (passports etc...).

The main route of "policing" citizenship is through proof-of-identification, which you would need to be able to obtain services from government, or travel to other countries. If you do not have a citizenship with which you can apply for a valid form of identification, then you would have to declare yourself "stateless".

You may also be required to be associated with a nation for legal purposes when they come up. But it's entirely feasible to live on earth without ever having citizenship - it's up to the authority where you live to accept you without citizenship.

It is completely possible to have multiple citizenships. The restrictions on multiple citizenships are applied by a nation to its citizens - if you do not tell them that you have other citizenships, they will not know unless someone else tells them, but you might be breaking some disclosure law by keeping said information secret.

An easy example of someone with multiple citizenships would be:

A child born in the Canada, to Australian parents, who then obtains the citizenship of the United Kingdom by immigrating (three citizenships).

  • 2
    “several agreements…” is a big part of what's called “international law”.
    – Relaxed
    Feb 20, 2017 at 21:25

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