Since his second inauguration in January, Donald Trump has issued more than 160 executive orders. These orders permit the US president to make directives concerning the workings of the federal government without the need to pass laws in Congress. All US presidents have used them, including George Washington, but Trump has issued his orders at an unprecedented rate.

A number of these have courted controversy. But one stands out in particular: executive order 14160. This was signed on the day of his inauguration, January 20, and seeks to end birthright citizenship for children born in the US where the parents are in the country illegally or on temporary visas.

The purpose of this order was to redefine the scope of the 14th amendment to the constitution. This states that: “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.” Trump’s executive order sets limits on that principle.

Due to the order’s conflict with the constitution, various district courts have issued what are known as “universal injunctions”, blocking the order. In response to these injunctions, the government brought a case in the Supreme Court: Trump v Casa. The Trump administration argues that district judges should not have the power to issue such wide-ranging injunctions which effectively limit the president’s power.

Get your news from actual experts, straight to your inbox. Sign up to our daily newsletter to receive all The Conversation UK’s latest coverage of news and research, from politics and business to the arts and sciences.

On June 27 the Supreme Court delivered its judgment. It found in favour of the government, holding that: “Universal injunctions likely exceed the equitable authority that Congress has given to federal courts.” The court stopped short of banning them outright – but it effectively limited the extent to which courts could issue a universal block on the president’s executive orders.

The judgment did not decide on the constitutionality of the executive order itself, but focused solely on the limits of judicial power to block presidential actions more broadly. So the question of birthright citizenship remains unresolved.

People affected can bring personal lawsuits and there is also the avenue of “class action suits” in which a number of people who have grouped together with common cause and been have been ruled by a judge to constitute a “class” can seek legal relief. The New York Times has reported that plaintiffs are how preparing to refile suits to challenge executive order 14160.

But the issue raises questions about the Supreme Court. In the US, the nine Supreme Court justices are nominated by the president, and inevitably bring a corresponding political outlook to their work. Currently, there are six conservative judges – three of whom were appointed by Trump in his first term of office – and three liberal judges.

In Trump v Casa, the court divided on ideological lines. The six conservative judges supported the majority view, while the three liberal judges dissented. This was not entirely unexpected. But the ruling raises the more fundamental question about the vital constitutional role that courts play in acting as a check on government power.

Cornerstone of democracy

In democracies around the world, constitutional principles ensure that power is exercised according to law and that the various holders of legislative, executive, and judicial power do not exceed their authority. Central to these arrangements is the role of the courts. While judges must be careful not to involve themselves in the policy decisions of government, or the law-making deliberations of a legislature, it is their duty to ensure the executive does not act unlawfully or the legislature unconstitutionally.

Case reports across the world are littered with examples of judges reviewing and, on occasion, striking down government or legislative action as unlawful. In the US, the seminal case of Marbury v Madison (1803) which established, for the first time, that the Supreme Court should have the power to strike down an act of Congress as unconstitutional, has served as a beacon of this principle for over 200 years. In the UK, the Supreme Court’s finding in R(Miller) v Prime Minister that the government’s 2019 prorogation of parliament was unlawful provides a notable example of the continued importance of this role.

The balance that the courts must strike in not interfering in the policy decisions of government on the one hand, and their fundamental role in acting as a check on the lawful use of power on the other is at the heart of Trump v Casa. In the Supreme Court’s written majority opinion, Justice Amy Coney Barrett, held that the use of “universal injunctions” by the district courts was an example of judicial overreach. She wrote that federal judges were going beyond their powers in seeking to block the universal application of the executive order.

The dissenting three liberal justices issued a minority opinion saying that this finding was at odds with the rule of law. Indeed, Justice Sonia Sotomayor said the ruling in Trump v Casa “cannot coexist with the rule of law. In essence, the Courts has now shoved lower court judges out of the way in cases where executive actions is challenged, and has gifted the Executive with the prerogative of sometimes disregarding the law.”

The finding of the Supreme Court, in other words, has arguably limited the extent to which the courts in America can serve as a check on the exercise of executive power. Trump hailed the Supreme Court’s decision as a “giant win”, while attorney general Pam Bondi said it would “stop the endless barrage of nationwide injunctions against President Trump”.

Here’s the nub of the affair: while courts must be able to act as a check on the lawfulness of government action, at the same time, a government must be able to govern without too frequent or too onerous obstructions from the judiciary and this finding potentially gives the Trump administration greater room for manoeuvre.

But there is a further issue. As mentioned, US Supreme Court justices are nominated by the president. With the justices of the court being divided on political lines in Trump v Casa, questions can fairly be asked about the propriety of this arrangement – and whether it was always inevitable that one day there would be a Supreme Court in which the people might lose faith because they felt that it was more beholden to ideology than the law.

This is a potentially dangerous moment in the US. The independence of the judiciary has long been a bulwark against abuses of power – and has been regarded as such by the US people. Having judges nominated by those holding political office arguably hinders that independence – and, as the judgment in this case suggests, could throw into jeopardy the invaluable role that the courts play in keeping the exercise of government power in check.

John Stanton does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.