With a Congress controlled by Trump's fellow Republicans largely falling in line behind his agenda, federal judges often have emerged as the only constraint on the president's torrent of executive actions since his January inauguration.
Trump this week responded to U.S. District Judge James Boasberg's order aimed at halting his administration's swift deportation of alleged Venezuelan gang members by calling for the judge to be impeached by Congress - a process that could lead to removal from the bench. Trump's statement drew a rebuke from U.S. Chief Justice John Roberts.
The nation's founders set up a system of government in the Constitution with three co-equal branches, a design intended to have the executive, legislative and judicial branches serve as a check on the power of the others.
Georgetown University law professor David Super said Trump "clearly is making a very aggressive move to expand presidential powers at the expense of the other two branches of government."
The Trump administration's remaking of the constitutional order is "happening in incremental steps," according to American University Washington College of Law professor Elizabeth Beske.
The Trump administration has argued that it is the judiciary, not the president, that is overreaching. Trump urged the Supreme Court on Thursday to limit the ability of federal judges to issue injunctions blocking his administration's actions nationwide.
"STOP NATIONWIDE INJUNCTIONS NOW, BEFORE IT IS TOO LATE," Trump wrote in a social media post. "If Justice Roberts and the United States Supreme Court do not fix this toxic and unprecedented situation IMMEDIATELY, our Country is in very serious trouble!"
UNITARY EXECUTIVE THEORY
Trump is also aiming to weaken checks within the executive branch, according to legal experts, including by firing the inspectors general and the heads of various agencies designed by Congress to have a measure of independence from a president's direct control.
Some of Trump's broad assertions of power are in line with what is called the "unitary executive" theory. This conservative legal view sees the president as possessing vast authority over the executive branch - even when Congress has sought to impose limits such as protecting the heads of independent agencies from firing without cause.
John Yoo, a proponent of the unitary executive, said Trump is seeking to return presidential power to dimensions that existed prior to reforms enacted by U.S. lawmakers after the Watergate political scandal that prompted Republican President Richard Nixon's 1974 resignation. These reforms, Yoo said, added to the power of Congress at the expense of presidential authority.
"We can understand many of Trump's actions as attempts to undo the Watergate reforms and restore full presidential control over the executive branch," said Yoo, who served as a Justice Department lawyer under Republican President George W. Bush and is now a professor at the University of California, Berkeley School of Law.
Still, Trump faces little pushback from the current Republican-led Congress. According to Benjamin Schneer, a professor of public Policy at the Harvard Kennedy School, this largely tracks a decades-long trend of the United States moving away from the "separation of powers," as envisioned in the Constitution, to the "separation of parties," amid deepening mistrust between the two major American political parties.
That dynamic has been amplified since Trump's return to the White House, as Congress has largely relinquished its role as a meaningful check on the executive, Schneer said, adding: "This is a new world that we're in right now."
"Congress doesn't seem to be particularly interested in curbing the powers of the executive, and so lawsuits are brought challenging the president's use of this authority," Thomas Griffith, a former federal appeals court judge appointed by Bush, said during a panel discussion hosted by the American Academy of Arts & Sciences.
Trump's authority to remove executive branch officials has been challenged in court following Trump's firings at the Merit Systems Protections Board, Federal Labor Relations Authority, Privacy and Civil Liberties Oversight Board, inspectors general offices and other agencies.
Trump secured a legal victory on this front when a federal appeals court allowed him to fire Hampton Dellinger as head of the U.S. Office of Special Counsel watchdog agency. That court concluded that Dellinger wielded significant executive power that made him removable at-will, including by working to halt mass firings of government workers by Trump's administration.
RULINGS AGAINST TRUMP
More than 100 lawsuits challenging actions by Trump and his administration are moving through federal courts. So far, dozens of rulings have been issued by judges - many but not all of them appointees of Democratic presidents - to impede actions such as Trump's bid to curtail automatic birthright citizenship, freeze federal funding, remove various government officials and ban transgender troops in the military.
Some experts said the administration is demonstrating a resistance to judicial orders not seen from recent administrations.
"This cannot be stressed enough - up until this point, we have not, in modern times, had to wonder whether a presidential administration would comply with a court order," said Duke University School of Law professor Marin Levy, who studies the federal judiciary.
Administration officials and Justice Department lawyers have disputed accusations of noncompliance.
Asked during a Fox News interview whether he would defy a court order, Trump said: "No, you can't do that."
"However, we have bad judges," Trump added. "We have very bad judges. These are judges that shouldn't be allowed. I think at a certain point, you have to look at what do you do when you have a rogue judge."
Trump allies in the House have sought to move ahead with impeachment of judges who ruled against him.
The Supreme Court has not yet ruled on the legal merits of any of the challenges to Trump's actions in his second term, meaning the degree to which it might act to check the president's authority remains unclear. Thus far, the top U.S. judicial body has dealt Trump temporary setbacks in a pair of procedural rulings.
The Supreme Court, whose 6-3 conservative majority includes three justices appointed by Trump during his first term, is currently weighing Trump's March 13 request for it to intervene in his bid to restrict birthright citizenship.
Seattle-based U.S. District Judge John Coughenour called Trump's birthright citizenship order "blatantly unconstitutional" and voiced alarm about the president's actions.
"There are moments in the world's history where people look back and ask, 'Where were the lawyers, where were the judges?" Coughenour said at a February 6 hearing. "In these moments, the rule of law becomes especially vulnerable. I refuse to let that beacon go dark today."
