The declaration by a senior adviser to President Trump that the administration is considering suspending the Great Writ of habeas corpus could set off a constitutional clash not seen since the days of President Lincoln. 

Stephen Miller, an immigration hawk, told reporters on Friday on the White House driveway: “The Constitution is clear, and that, of course, is the supreme law of the land, that the privilege of the writ of habeas corpus can be suspended at a time of invasion. So I would say that’s an action we’re actively looking at.”

Habeas corpus is a legal procedure that allows for the challenging of unlawful detention. It is a summons with the force of a court order addressed to the custodian supervising the detention and demands that a prisoner be brought before a court where his petition can be heard. One of the so-called extraordinary writs, Alexander Hamilton wrote that it provided “perhaps greater securities to liberty and republicanism” than any clause of the parchment.

Mr. Miller, who serves as Mr. Trump’s homeland security adviser and White House deputy chief of staff for policy, has been floated — with seeming interest from the president — as Congressman Mike Waltz’s successor as national security adviser. The post is vacant after Mr. Trump announced his intention to relocate the Floridian to ambassador to the United Nations.

The allusion by the high-flying Mr. Miller is to Article I, Section 9 of the Constitution, which ordains: “The Privilege of the Writ of Habeas Corpus shall not be suspended, unless when in Cases of Rebellion or Invasion the public Safety may require it.” Mr. Miller suggested that whether the administration moves to suspend habeas will depend on “whether the courts do the right thing.”

Habeas corpus, Latin for “you have the body,” can date its origins to the reign of the Assize of Clarendon of 1166, a reissuance of rights by King Henry II. The assize is credited with jump-starting the development of trial by jury and bringing to a close the era where guilt or innocence was determined by combat or ordeal, practices that can be discerned as far back as Hammurabbi’s Code.

Mr. Trump, CNN reports, has been personally involved in discussions to suspend habeas. At the end of April he told reporters in respect of judicial resistance to his immigration efforts that there “are ways to mitigate it and there’s some very strong ways. There’s one way that’s been used by three very highly respected presidents, but we hope we don’t have to go that route.”

Mr. Trump’s allusion appears to be to Lincoln, who suspended habeas during the Civil War, President Theodore Roosevelt, who did the same in the Philippines during an uprising there in 1905, and President Franklin Roosevelt, who suspended the writ in Hawaii after the bombing of Pearl Harbor. Lincoln’s first attempt at suspending the writ, without Congress, was struck down by Chief Justice Taney. That precipitated a conflict with the court.  

Only when the Great Emancipator obtained congressional authorization was his suspension approved by the courts. The law passed by Congress mandated that “during the present rebellion, the President of the United States, whenever in his judgment the public safety may require it, is authorized to suspend the privilege of the writ of habeas corpus in any case throughout the United States.” Lincoln used it in cases involving members of the military, prisoners of war, spies, traitors, and in all of Kentucky. 

Just as the federal courts initially stymied Lincoln’s attempt to suspend habeas, so too have courts frustrated Messrs. Trump and Miller’s preferred policy on immigration. The Supreme Court ruled last month that illegal aliens that the government is attempting to deport under the 1798 Alien Enemies Act are entitled to some rudiments of due process and the opportunity to file habeas petitions. The Trump administration alleges that these aliens are members of Tren de Aragua, a designated terror organization.

The Supreme Court could yet be called on to address head on the president’s power to suspend habeas corpus without congressional approval. The Suspension Clause’s placement in Article I suggests that the Founders considered it to be within the ambit of the legislature. As a legal scholar, Seth Barrett Tillman, explains, “Chief Justice Taney expressed the view that the President had no unilateral power to suspend habeas corpus. In other words, under the Constitution, only Congress can suspend habeas corpus.”

A narrow view on the reach of habeas was articulated by a onetime deputy assistant attorney general in the  Office of Legal Counsel of the Department of Justice, John Yoo. He argued in a series of memoranda that enemy combatants were not entitled to file writs of habeas corpus. The Supreme Court, though, in Boumedine v. Bush held that prisoners at Guantanamo Bay were entitled to challenge their confinement under habeas. 

The constitutional text does not explicitly specify who is entitled to suspend habeas — only that it is to remain in force save in instances of “rebellion or invasion.” Last week federal judges in New York and Colorado both ruled that the Trump administration had failed to meet the bar for proving the presence of an “invasion,” as would appear to be required by both the Alien Enemies Act and the Suspension Clause. 

One of the judges, Alvin Hellerstein, who halted the use of the Alien Enemies Act, wrote in his ruling: “There is nothing in the” act that “justifies a finding that refugees migrating from Venezuela …  are engaged in an ‘invasion’ or ‘predatory incursion.’ They do not seek to occupy territory, to oust American jurisdiction from any territory, or to ravage territory.” That suggests that Mr. Trump is required to argue for an invasion, not just assert one.  

A liberal legal sage, Steven Vladeck, writes on his Substack that Mr. Miller’s musings with respect of habeas are “factually and legally nuts,” and called them the “most remarkable (and remarkably scary) comments about federal courts that I think we’ve ever heard from a senior White House official.”

That view appears to have been anticipated by Justice Sandra Day O’Connor, who in Hamdi v. Rumsfeld’s majority opinion wrote that only “in the rarest of circumstances has Congress seen fit to suspend the writ. … At all other times, it has remained a critical check on the Executive, ensuring that it does not detain individuals except in accordance with law.”