The Supreme Court is expected to decide one of the most consequential cases in modern US history on Friday – whether a single federal judge can block an order from the US president from taking effect nationwide.

The case stems from President Donald Trump’s bid to end birthright citizenship, which has been frozen by multiple lower courts.

The Supreme Court is not likely to rule on the constitutionality of birthright citizenship itself. It will instead focus on federal judges’ use of nationwide injunctions, which have stunted key aspects of Trump’s agenda.

The Trump administration has argued that the judges have overstepped their power, but others say the injunctions are needed to avoid “chaos”.

On his first day back in office, Trump signed an executive order aimed at ending automatic citizenship rights for nearly anyone born on US territory – commonly known as “birthright citizenship”.

The move was instantly met by a series of lawsuits that ended in judges in district courts in Maryland, Massachusetts and Washington state issuing nationwide injunctions that blocked the order from taking effect.

In Washington, US District Court Judge John Coughenour called Trump’s executive order “blatantly unconstitutional”.

Trump’s Department of Justice responded by saying the case did not warrant the “extraordinary measure” of a temporary restraining order and appealed the case to the Supreme Court.

Injunctions have served as a check on Trump during his second term, amid a flurry of executive orders signed by the president.

Roughly 40 different court injunctions have been filed this year. This includes two lower courts that blocked the Trump administration from banning most transgender people from the military, although the Supreme Court eventually intervened and allowed the policy to be enforced.

So the case being heard at the nation’s highest court is not about birthright citizenship directly – but about whether lower courts should have the authority to block nationwide presidential orders with injunctions.

The issue of nationwide injunctions has long troubled Supreme Court justices across the ideological spectrum.

Conservative and liberal justices alike have argued that a judge in one district should not be able to unilaterally decide policy for the entire country.

Liberal Justice Elena Kagan said in remarks in 2022: “It can’t be right that one district judge can stop a nationwide policy in its tracks and leave it stopped for the years that it takes to go through the normal process.”

Similarly, conservative Justice Clarence Thomas once wrote that “universal injunctions are legally and historically dubious”.

Injunctions are also criticised for enabling what is known as forum shopping – the practice of filing a lawsuit in a jurisdiction where a more favourable ruling is likely.

Another critique of injunctions is the speed at which they are delivered versus their far-reaching impact.

The Trump administration is arguing in the birthright citizenship case that lower judges did not have the right to put time-consuming legal obstacles in front of the Trump’s agenda.

Without nationwide injunctions, backers of the measure say the power of the executive branch could go unchecked and leaves the burden of protection from potentially harmful laws on individuals who would need to file separate lawsuits.

Injunctions are often the only legal mechanism to prevent Trump’s executive orders from taking immediate legal effect. Such orders are a marked contrast from laws passing through Congress, which takes longer and subjects them to additional scrutiny.

Liberal Justice Ketanji Brown Jackson said the Trump administration’s argument advocated for a “catch me if you can” justice system.

“Your argument says ‘we get to keep on doing it until everyone who is potentially harmed by it figures out how to file a lawsuit, hire a lawyer, etc,'” Jackson said.

“I don’t understand how that is remotely consistent with the rule of law,” she said.

The other argument for injunctions is that it allows for consistency in the application of federal laws.

Lawyers arguing against the Trump administration have said that, in the birthright citizenship case, there would be “chaos” in the absence of a nationwide injunction, creating a patchwork system of citizenship.

The first sentence of the 14th Amendment to the US Constitution establishes the principle of birthright citizenship.

“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.”

However, the Trump administration’s arguments rest on the clause in the 14th Amendment that reads “subject to the jurisdiction thereof”. It argues that the language excludes children of non-citizens who are in the US unlawfully.

Most legal scholars say President Trump cannot end birthright citizenship with an executive order.

At the 15 May hearing, Justice Kagan noted that the administration had lost on the birthright citizenship issue in every lower court and asked: “Why would you ever take this case to us?”

On nationwide injunctions, the justices could say injunctions can only apply to the people who sued, including class actions, as government lawyers have advocated for.

The justices could also say injunctions can only apply in the states where the cases are brought, or that injunctions can only be issued on constitutional questions (like birthright citizenship).

Constitutional questions, though, concern the bulk of the cases with nationwide injunctions that the Trump administration is appealing.

If the court rules the injunctions should be lifted, then the Trump administration could deny birthright citizenship to children of undocumented immigrants while the court cases proceed.

If the injunctions hold, the individual court cases challenging the birthright citizenship order will likely work their way to the Supreme Court.

The high court could decide on the constitutionality of birthright citizenship, but justices have indicated they would prefer a separate, full hearing on the question.

They could also give indications or hints in their written opinion on which way they are leaning on the citizenship question, without ruling directly on it.