Donald Trump's fight to end automatic citizenship for people born in the United States has reached the Supreme Court, with justices grappling with whether to maintain a freeze on his attempt.
Within days of becoming US president, Mr Trump signed an executive order that tried to put an end to a widely-held constitutional interpretation that guaranteed US citizenship to most people born in the country, including the children of undocumented immigrants.
He signed the order back in Janaury, but it hasn't been enforced yet because of legal action.
Now, months later, this issue is before the highest court in the land, but what's being debated is complicated.
Here's what you need to know.
What is birthright citizenship?
It's US citizenship granted to a person because they were born in the US.
This is based on the wording of the US Constitution, specifically in the 14th Amendment, which states:
"All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside."
Can Trump end birthright citizenship?
That's unclear.
It's a question further court challenges are aiming to test.
Mr Trump's executive order conflicts with a Supreme Court decision from 1898 that held that the Citizenship Clause of the 14th Amendment made citizens of all children born on US soil (with narrow exceptions that aren't an issue in this case).
Almost immediately after Mr Trump signed the order, 22 states as well as immigrants and rights groups launched legal action against it.
Judges from three federal courts — which are a on a lower level to the Supreme Court — blocked the enforcement of the order while the lawsuits proceeded.
They did this by issuing court orders which applied nationwide — which you might hear being referred to as "universal injunctions".
The current fight in the Supreme Court is about whether federal court judges have the ability to make those broad, nationwide orders.
It's also about what rules will apply while those lawsuits we mentioned earlier unfold.
What happened in court?
There was a hearing in in front of the nine justices of the Supreme Court — but a decision hasn't been made yet.
The two-hour hearing was about the Trump administration's emergency appeal requesting the Supreme Court to scale back the injunctions.
It wants the Supreme Court to say the injunctions only apply to those launching legal action over the order — meaning individual plaintiffs and the 22 states.
That would mean the executive order would be carried out in the 28 states that did not sue.
Several of the justices raised concerns that this would result in a confusing patchwork of rules.
The court seemed keen to allow the orders preventing Mr Trump's administration from enforcing his executive order, AP reported.
However, it appeared to be willing to look at ways to scale back nationwide court orders.
The majority expressed concerns about what would happen if Mr Trump's administration was allowed, even temporarily, to deny citizenship to children born to people who are in the US illegally.
None of the justices signalled an endorsement of Mr Trump's order, Reuters pointed out.
A decision is expected by the end of June.
Can an executive order change the US Constitution?
No.
But Mr Trump's team isn't arguing to change the 14th Amendment — it wants to change the way the wording of the amendment is interpreted.
Amending the constitution could take years, and would need support from two-thirds of both the US House of Representatives and the Senate.
Alternatively, a constitutional convention could be held.
But either way, change would also need approval by three-quarters of the state governments within the US.
"The Founding Fathers, in crafting the Constitution, believed it should not be easy to amend the nation's founding document and principles," the US National Conference of State Legislatures website says.
Why does Trump want to change the rules?
It's all part of his crackdown on both undocumented and legal immigrants.
During the presidential campaign, Mr Trump's mass deportation plans were a key promise,
Mr Trump has said for years that he wants to end birthright citizenship, calling it "birth tourism" and "absolutely ridiculous".
Birth tourism is a term Republicans use when claiming people visit the US toward the end of a pregnancy in order to ensure the child is born a citizen.
Back when Mr Trump was president in 2018, he spoke in an interview with Fox News about some of his hardest-line immigration ideas.
An executive order on birthright citizenship was one of them.
In a recent post to his social media platform, Truth Social, the president called the US "stupid" for allowing birthright citizenship.
"Birthright citizenship was not meant for people taking vacations to become permanent Citizens of the United States of America, and bringing their families with them, all the time laughing at the "SUCKERS" that we are," he wrote.
He also claimed birthright citizenship had been exploited by illegal immigrants, adding: "The drug cartels love it."
What does the executive order say?
Essentially, it said the meaning of the words in the 14th Amendment don't mean everyone born in the US should be a citizen.
It also directed federal agencies to refuse to recognise the citizenship of US-born people who didn't have at least one parent who was either an American citizen or a lawful permanent resident.
Here's some of the wording of Mr Trump's executive order, titled Protecting the Meaning and Value of American Citizenship:
"The Fourteenth Amendment has never been interpreted to extend citizenship universally to everyone born within the United States.
"The Fourteenth Amendment has always excluded from birthright citizenship persons who were born in the United States but not 'subject to the jurisdiction thereof'."
It goes on to say that citizenship shouldn't be granted:
(1) when that person's mother was unlawfully present in the United States and the father was not a United States citizen or lawful permanent resident at the time of said person's birth, or
(2) when that person's mother's presence in the United States at the time of said person's birth was lawful but temporary (such as, but not limited to, visiting the United States under the auspices of the Visa Waiver Program or visiting on a student, work, or tourist visa) and the father was not a United States citizen or lawful permanent resident at the time of said person's birth
These claims have been heavily contested by legal experts and many states, leading to the current court challenge.
ABC with Wires
