After meeting wrongly deported man, Van Hollen accuses Trump of defying courts.

Mr. Van Hollen, a Maryland Democrat, traveled to El Salvador last week to press for the release of the man, Kilmar Armando Abrego Garcia, who was deported to a notorious Salvadoran prison in March in what an administration lawyer described as an “administrative error.”

A federal appeals court on Thursday ordered the Trump administration to take a more active role in bringing back Mr. Abrego Garcia, a few days after the Supreme Court ruled that the government should “facilitate” his return from El Salvador.

Instead, the White House has publicized an allegation of domestic abuse from Mr. Abrego Garcia’s wife from 2021, when she sought a protective order. Mr. Abrego Garcia’s wife said last week that the two “were able to work through this situation privately.”

The administration also cited a police filing from a Tennessee trooper who stopped Mr. Abrego Garcia on a highway in 2022 and raised suspicion of human trafficking. Federal law enforcement officials instructed the trooper not to detain him, and Mr. Abrego Garcia’s wife has said he routinely drove workers to their jobs.

“What Donald Trump is trying to do is change the subject,” Mr. Van Hollen said on Sunday. “Put up or shut up in court instead of litigating this through social media.”

He added, “If you have evidence, take it to the court.”

On Wednesday, Karoline Leavitt, the White House press secretary, also brought Patty Morin, the mother of Rachel Morin, who was killed by an undocumented immigrant, to a press briefing to lay out details about the brutal murder — a case unrelated to Mr. Abrego Garcia.

A federal judge has described the government’s claims accusing Mr. Abrego Garcia of being a member of the transnational street gang, MS-13, as “unsubstantiated” and as based on “nothing more than his Chicago Bulls hat and hoodie.”

On Sunday, Mr. Van Hollen expressed his sympathies toward Ms. Morin’s family while emphasizing the importance of ensuring due process for all of those in the United States.

“I’m very glad that the killer of Rachel has been convicted in a court of law — that is how we hold guilty people accountable,” Mr. Van Hollen said.

“You can crack down and hold guilty people accountable and also respect the due process rights of everybody who is in court,” he added. “I am not sure why Abrego Garcia’s rights should be denied based on an awful murder that he had absolutely nothing to do with.”

In multiple TV appearances on Sunday, Mr. Van Hollen warned that the outcome of Mr. Abrego Garcia’s case could ultimately threaten the constitutional rights of U.S. citizens.

“When you trample on the constitutional rights of one man, you threaten the constitutional rights of every American,” he said. “This is not a case about just one man whose constitutional rights are being ignored and disrespected.”

Mr. Van Hollen also responded to some Democrats who were critical of his trip and the attention Mr. Abrego Garcia’s case has generated, including Gov. Gavin Newsom of California, who called the issue “a distraction” from economic issues such as President Trump’s tariffs.

“I think Americans are tired of elected officials or politicians putting a finger to the wind,” Mr. Van Hollen said, when asked specifically about Mr. Newsom’s comment. “Anyone who can’t stand for the constitution doesn’t deserve to lead.”

The court’s unsigned, one-paragraph order came after a fast-moving legal battle late Friday. The American Civil Liberties Union had rushed to several lower courts, then to the Supreme Court, claiming that the Trump administration was planning to deport more Venezuelan migrants, presumably to El Salvador, with little to no due process under the wartime law, the Alien Enemies Act.

The Supreme Court’s decision ordered a pause on the deportations of the detainees while it considers the emergency application.

The order suggested a deep skepticism on the court about whether the Trump administration could be trusted to live up to the key part of an earlier ruling that said detainees were entitled to be notified if the government intended to deport them under the law, “within a reasonable time,” and in a way that would allow the deportees to challenge the move.

“In sum, literally in the middle of the night, the court issued unprecedented and legally questionable relief,” Justice Alito wrote in his dissent, “without giving the lower courts a chance to rule, without hearing from the opposing party, within eight hours of receiving the application, with dubious factual support for its order, and without providing any explanation for its order.”

Justice Alito said that he had refused to join the court’s order because “we had no good reason to think that, under the circumstances, issuing an order at midnight was necessary or appropriate.”

The matter reached the Supreme Court this weekend after lawyers said the Trump administration was preparing to deport another group of detained Venezuelan migrants in Texas without giving them a chance to contest their removal. The Supreme Court temporarily blocked their removal, apparently concerned that their access to a form of court hearing — habeas corpus relief — might be denied.

In another case, the Trump administration deported a Maryland man to El Salvador in what the administration initially acknowledged was a mistake. A federal judge ordered the government to facilitate the return of the man, Kilmar Armando Abrego Garcia, but it has not done so.

Here’s what the terms due process and habeas corpus mean, and why they matter.

What is due process?

Due process is the idea that people should have access to fair treatment before the law. It forbids convictions without a fair trial, for example, and it requires law enforcement officials to make criminal suspects aware of their right against self-incrimination and their right to have a lawyer present.

The Fifth Amendment to the U.S. Constitution says that no person shall be “deprived of life, liberty, or property, without due process of law.” The 14th Amendment contains a similar clause.

Courts have long held that anyone in the United States, regardless of citizenship or immigration status, has a right to due process under the Constitution.

“For example, a green card holder cannot be summarily deported from the United States without some kind of hearing before an immigration judge, and that hearing has to be fundamentally fair,” said Stephen Yale-Loehr, a retired immigration law professor at Cornell University. “Normally.”

Why is this coming up now?

The Trump administration has sought to skirt the promise of due process by invoking the Alien Enemies Act of 1798, a powerful but rarely used law. The administration alleges that a Venezuelan gang, Tren de Aragua, is invading the United States.

The administration’s critics say the government is manufacturing an emergency to trample on core rights. Senator Chris Van Hollen, a Maryland Democrat who visited Mr. Abrego Garcia in El Salvador last week, said his case was about the “fundamental principle in the Constitution” of due process.

At an anti-Trump protest in Manhattan on Saturday, one sign carried two words: “Due Process.”

The American Civil Liberties Union sued the administration, arguing that it had improperly invoked the Alien Enemies Act in peacetime. The Supreme Court denied the advocacy group’s initial challenge, saying it had been filed in the wrong court. But it also said that anyone targeted for deportation under the law should be allowed habeas relief, or a court hearing, before being expelled.

The decision set off a scramble by the A.C.L.U. to prevent further deportations without hearings, and the group is now involved in litigation over the Alien Enemies Act in at least nine courts.

In court, the cases have turned more on procedural questions than on due-process principles. But another legal concept, habeas corpus, has emerged as a central issue.

You lost me. What is habeas corpus?

Habeas corpus is an ancient concept that predates the Constitution, Mr. Yale-Loehr said. It means that people who are in government custody have a right to challenge their status in a court hearing, called a habeas corpus proceeding.

A writ of habeas corpus from a judge requires the government to produce an individual in custody for a hearing.

Habeas corpus, which means “you should have the body” in Latin, has been the primary way that federal courts have reviewed the constitutionality of criminal convictions in state courts. And it is an important tool for immigrants to avoid unlawful detentions and deportations.

The principle is derived from centuries of common law, the type of law created by court cases rather than a legal code. But the Constitution also says that habeas corpus can be suspended “when in Cases of Rebellion or Invasion the public Safety may require it.”

So what’s the connection to these cases?

Some legal scholars say that the government deprived Mr. Abrego Garcia of the right to a habeas corpus hearing by sending him to a foreign prison.

In the Alien Enemies Act case, the A.C.L.U. said in court papers on Friday that the administration appeared to be on the cusp of carrying out more deportations while depriving Venezuelan migrants in U.S. custody of the chance to contest their removals. The Supreme Court issued its temporary order blocking deportations hours later.

A lawyer for the government said in a filing on Saturday afternoon that the Supreme Court’s order was “premature” and that detainees had “adequate time to file” claims challenging their removal.

The meeting came after the pope criticized the Trump administration’s deportation policies and urged Catholics to reject anti-immigrant narratives, in an unusually direct attack on the American government.

The rebuke came in the form of an open letter to American bishops in February, with some of the pope’s criticisms apparently leveled directly at statements made by Mr. Vance.

Mr. Vance, who was baptized as a Catholic six years ago, has been spending Holy Week in Rome with his family. He attended the Good Friday service in St. Peter’s Basilica. On Saturday, Mr. Vance met with Cardinal Pietro Parolin, the Vatican’s secretary of state, and with Archbishop Paul Gallagher, the Vatican’s foreign minister.

Mr. Vance had not been expected to meet the pope, who only recently left the hospital after spending five weeks there in serious condition. The pope has made unannounced appearances since his hospital stay, but his health tightly restricts his planned engagements.

“I know you have not been feeling great but it’s good to see you in better health,” Mr. Vance told the pope, according to video footage of the visit. An aide to the pope handed Mr. Vance gifts, including three chocolate Easter eggs for his children, a tie with the Vatican’s emblem and rosaries. “I pray for you every day,” Mr. Vance told the pope before he left.

The two met at Casa Santa Marta, the pope’s residency, as the Sunday mass continued in St. Peter’s Square with a cardinal presiding over the liturgy in place of Francis. The pope later appeared on the balcony of St. Peter’s Basilica, waved at the tens of thousands gathered below, and wished them a happy Easter.

In a message read to the crowds by an aide in St. Peter’s Square, Pope Francis reiterated his condemnation of anti-immigrant positions.

“How much contempt is stirred up at times towards the vulnerable, the marginalized, and migrants!” he wrote.

Before entering the hospital, the pope, a staunch advocate for migrants and refugees, had directed a sharp critique toward President Trump over his administration’s immigration policy, saying that deporting people who come from difficult situations violates the “dignity of many men and women, and of entire families.”

In those remarks, the pope appeared to give a riposte to Mr. Vance, who has defended the deportation policies by referring to the Christian concept of “ordo amoris” — which he defined as a hierarchy of duties that prioritizes immediate obligations to one’s family or community over more distant needs. “The true ordo amoris that must be promoted” is “love that builds a fraternity open to all, without exception,” Francis wrote in his open letter to American bishops.

Speaking at the National Catholic Prayer Breakfast in February, Mr. Vance acknowledged the pope’s critical comments, but said he would continue to express his views.

During the meeting between Mr. Vance and the Vatican officials on Saturday, “there was an exchange of opinions” on “difficult humanitarian situations, with particular attention to migrants, refugees, and prisoners,” among other issues, according to a statement from the Vatican.

It was not immediately clear who had compiled the document or what stage of internal debates over a restructuring of the State Department it reflected. It is one of several recent documents proposing changes to the department, and internal administration conversations take place daily on possible actions.

Some of the ideas have been debated among U.S. officials in recent weeks, though it is unclear to what degree they would be adopted or how active the draft is, officials said.

Elements of the draft executive order could change before final White House review or before President Trump signs it, if he decides to do so.

Secretary of State Marco Rubio wrote a short comment on social media after this article was published, calling it “fake news.” There are no indications that Mr. Rubio or his top aides have signed off on the document, though they have been working on a reorganization of the State Department.

Neither the State Department nor the White House National Security Council replied to requests for comment early Sunday before this article was published, including a question asking whether Mr. Trump would sign such an executive order.

The purpose of the executive order is to impose “a disciplined reorganization” of the State Department and “streamline mission delivery” while cutting “waste, fraud and abuse,” according to a copy of the draft order obtained by The New York Times. The order says the department is supposed to make the changes by Oct. 1.

Some of the proposed changes outlined in the draft document would require congressional notification and no doubt be challenged by lawmakers, including mass closures of diplomatic missions and headquarters bureaus, as well as an overhaul of the diplomatic corps. Substantial parts, if officials tried to enact them, would likely face lawsuits.

The document began circulating among current and former U.S. diplomats and other officials on Saturday.

Major structural changes to the State Department would be accompanied by efforts to lay off both career diplomats, known as foreign service officers, and civil service employees, who usually work in the department’s headquarters in Washington, said current and former U.S. officials familiar with the plans. The department would begin putting large numbers of workers on paid leave and sending out notices of termination, they said.

The draft executive order calls for ending the foreign service exam for aspiring diplomats, and it lays out new hiring criteria that includes “alignment with the president’s foreign policy vision.”

The draft says the department must greatly expand its use of artificial intelligence to help draft documents, and to undertake “policy development and review” and “operational planning.”

The proposed reorganization would get rid of regional bureaus that help make and enact policy in large parts of the globe.

Instead, the draft says, those functions would fall under four “corps”: Eurasia Corps, consisting of Europe, Russia and Central Asia; Mid-East Corps, consisting of Arab nations, Iran, Pakistan and Afghanistan; Latin America Corps, consisting of Central America, South America and the Caribbean; and Indo-Pacific Corps, consisting of East Asia, Southeast Asia, India, Bangladesh, Sri Lanka, Nepal, Bhutan and the Maldives.

One of the most drastic proposed changes is to eliminate the bureau of African affairs, which oversees policy in sub-Saharan Africa. It would be replaced by a much smaller special envoy office for African affairs that would report to the National Security Council. The office would focus on a handful of issues, including “coordinated counterterrorism operations” and “strategic extraction and trade of critical natural resources.”

The draft also said all “nonessential” embassies and consulates in sub-Saharan Africa would be closed by Oct. 1. Diplomats would be sent to Africa on “targeted, mission-driven deployments,” the document said.

Canadian operations would be put into a new North American affairs office under Mr. Rubio’s authority, and it would be run by a “significantly reduced team,” the draft said. The department would also severely shrink the U.S. embassy in Ottawa.

The department would eliminate a bureau overseeing democracy and human rights issues; one that handles refugees and migration; and another that works with international organizations. The under secretary position overseeing the first two bureaus would be cut. So would the office of the under secretary of public diplomacy and public affairs.

The department would also get rid of the position of the special envoy for climate.

The department would establish a new senior position, the under secretary for transnational threat elimination, to oversee counternarcotics policy and other issues, the draft memo said.

The Bureau for Humanitarian Assistance would absorb the remnants of the U.S. Agency for International Development, which has been gutted over the last two months by Mr. Rubio and other members of the Trump administration.

As for personnel, the memo said, the department needs to move from its “current outdated and disorganized generalist global rotation model to a smarter, strategic, regionally specialized career service framework to maximize expertise.”

That means people trying to get into the Foreign Service would choose during the application process which regional corps they want to work in.

The department would offer buyouts to foreign service and civil service officers until Sept. 30, the draft said.

The State Department has about 80,000 employees, with 50,000 of those being local citizens abroad. Of the rest, about 14,000 are trained diplomats who rotate overseas, called foreign service officers and specialists, and 13,000 are members of the civil service who work mostly out of Washington.

The draft order also calls for narrowing Fulbright scholarships so that they are given only to students doing master’s level studies in national security matters.

And it says the department will end its contract with Howard University, a historically Black institution, to recruit candidates for the Rangel and Pickering fellowships, which are to be terminated. The goal of those fellowships has been to help students from underrepresented groups get a chance at entering the Foreign Service soon after graduation.

The draft executive order is one of several internal documents that have circulated in the administration in recent days laying out proposed changes to the State Department. Another memo outlines a proposed cut of nearly 50 percent to the agency’s budget in the next fiscal year. Yet another internal memo proposes cutting 10 embassies and 17 consulates.

Greg Jaffe contributed reporting.

The deportations remain paused while the justices consider the matter. In emergency applications, the Supreme Court can act at any time.

In his filing, Mr. Sauer called the request by lawyers for the migrants that the justices step in “fatally premature” and argued that they had “improperly skipped over the lower courts.”

He said that the government had provided advance notice to detainees subject to imminent deportation and that they “have had adequate time to file” claims challenging their removal. Mr. Sauer added that the government had agreed it would not deport any detainees with pending claims.

The 17-page court filing came hours after a rare overnight ruling by the justices, who in a one-page, unsigned order had blocked the Trump administration from deporting the migrants.

It was the latest twist in a fast-moving, high-stakes legal battle over the administration’s efforts to deport Venezuelan migrants accused of being members of Tren de Aragua, a violent gang.

On Friday, lawyers for the American Civil Liberties Union mounted challenges in lower courts to prevent what they claimed was the imminent removal of Venezuelans who were scheduled to be flown out of the country from a detention center in Texas.

The lawyers then filed an emergency application with the Supreme Court, asking it to step in and temporarily block the deportations to protect the detainees as part of a proposed class action. The A.C.L.U. lawyers asked the court to move swiftly, claiming that some of the migrants had been loaded onto buses, presumably to be taken to the airport.

In his filing, Mr. Sauer said the A.C.L.U. had rushed to an appeals court and the Supreme Court without giving lower courts time to consider the case.

“Nonetheless, without waiting for the government to file its opposition brief and after giving the district court just 42 minutes to rule, applicants immediately sought emergency relief in the United States Court of Appeals for the Fifth Circuit and then in this court,” he wrote.

In their overnight order, the justices used formal language to request a response from the government. “The solicitor general is invited to file a response to the application before this court as soon as possible,” they wrote.

Mr. Sauer argued that the migrants had been given “adequate” notice of the government’s intent to deport them. He did not directly address claims by the A.C.L.U. that some of the notices were in English only, saying that “a detainee’s language ability or his family’s pre-existing relationship with a lawyer may well be relevant to a court’s determination of the adequacy of a particular notice.”

He also did not directly address the accusations that migrants might have been on buses and heading to the airport. The A.C.L.U. was “speculating” that migrants would be “removed imminently, before their claims can be further tested,” Mr. Sauer wrote.

He also pushed back against the group’s argument that the justices should protect the detainees as part of a proposed class action. The government had argued that the determination of whether a detainee under the Alien Enemies Act was entitled to court relief was “inherently too individualized” to treat them all as a class.

“Unnamed Pentagon officials have slandered our character with baseless attacks on our way out the door,” the three wrote in a highly unusual joint statement posted on social media.

The three all served in uniform. The social media message noted that two of them — Mr. Caldwell and Mr. Carroll — had served in combat in Iraq and Afghanistan. Mr. Caldwell and Mr. Selnick have known Mr. Hegseth, who brought them to the Pentagon, for more than a decade.

“Based on our collective service, we understand the importance of information security and worked every day to protect it,” the fired officials wrote.

They added that they had not been told what they were accused of leaking “or if there was even a real investigation of ‘leaks’ to begin with.”

Mr. Hegseth’s office has been plagued by infighting, dysfunction and occasional screaming matches since he took over in late January, said defense officials, speaking on the condition of anonymity to describe internal operations.

The three men described their experience over the past week as “unconscionable,” but said that they remained supportive of President Trump’s agenda and hoped to return to his administration.

In a letter explaining her veto, Governor Hobbs, a Democrat, said, “Arizonans, not Washington, D.C., politicians, must decide what’s best for Arizona.”

“I will continue to work with the federal government on true border security, but we should not force state and local officials to take marching orders from Washington, D.C.,” she added in the letter, addressed to Warren Petersen, the State Senate president.

Mr. Petersen, who sponsored the bill, called the measure “a vital action to help safeguard our communities” after legislators passed it earlier this month. He and other state Republican leaders were not available for comment on the veto on Saturday.

State Republicans had branded the bill as a necessary measure to “uphold the rule of law” against illegal immigration, arguing that anything short of it would be an affront to those who came to the country legally.

But state Democrats argued that the measure could lead to racial profiling and compromised due process rights. The Arizona House Democrats thanked the governor for vetoing the measure in a statement posted on X.

It was not clear whether legislators would try to override the veto. They would need a two-thirds majority.

Governor Hobbs’s veto comes as the Trump administration has ramped up its crackdown on immigration and as states across the country grapple with how, and whether, to cooperate with federal officials.

Because states have the ability to decide whether or not to work with them, there has been a patchwork of bills on this matter that have passed or are working through state legislatures.

In Florida, for instance, state lawmakers passed measures that take a harder stance on immigration, including one that set aside $250 million for local police departments to help federal officials. And in Alabama, the State House passed a bill this week that would empower local law enforcement to enforce federal immigration laws.

But in Colorado, the State Senate recently approved a bill that would limit local governments’ cooperation with federal officers.

The participants raged against the president, who they say is trampling on civil liberties and the rule of law, and overreaching in immigration, federal job cuts, the economy and other areas.

In front of the White House, protesters repeatedly shouted a single word.

“Shame!”

Thousands more marched from the Washington Monument. Many demonstrators berated the administration for not bringing Kilmar Armando Abrego Garcia, the Maryland man who the courts have said was wrongfully deported to El Salvador, back to the United States. Waving upside-down American flags, they marched along the eight-lane Constitution Avenue, chanting “Bring Kilmar home.” Trump officials have maintained that Mr. Abrego Garcia was a member of the Salvadoran gang MS-13; he denies the claim.

Julia Fine, a Maryland resident who was holding a sign at the protest by the White House that read “free Garcia,” said the prison in El Salvador where Mr. Abrego Garcia is being held reminded her of “concentration camps.”

“That’s where we’re headed with this,” she said.

Concerns over the government’s handling of Mr. Abrego Garcia’s case echoed at demonstrations from New York City to Cincinnati to Chicago.

At the protest in Manhattan, hundreds of signs flew in the air, including one that read: “Due Process.”

“It’s an injustice,” said Barry Knittle, 64, a manager at an engineering firm who lives in Mt. Kisco, N.Y. “And I fear it’s just the beginning.”

The crowd chanted, “The people united will never be defeated.” Packed double-decker tour buses passing by honked their horns in support, drawing big cheers.

Although many of the events on Saturday were traditional protests, many also were intended to unite local communities through activities such as food drives. Mass protests during President Trump’s first term, like the Women’s March in 2017, often focused on a single topic, but demonstrators on Saturday expressed concern on a wide range of issues: federal job cuts, their 401(k)s, veterans’ rights, Social Security, the war in Ukraine, transgender and gay rights, and misinformation on autism and vaccines.

“Everything here is a big issue,” said Fio Holloman, 22, who attended a rally in Chicago’s Daley Plaza.

Hundreds of protesters rallied in Fort Worth, at one point shutting down traffic for at least four blocks. Jeannie Walker, 54, couldn’t land on just one issue when asked what brought her to Saturday’s protest.

“All of it,” she said.

Aaron Burk, who attended the Washington rally and whose girlfriend took a federal buyout from the Department of Energy, said he was worried that the administration would not stop at deporting undocumented immigrants without due process and would imprison and deport U.S. citizens.

“Where does it stop?” he said. Mr. Burk added that his daughter is transgender and that he was most concerned about the dehumanization of minorities.

Hundreds took to the streets in Jacksonville, Fla., to protest a number of causes, including the president’s attacks on the L.B.G.T.Q. community and the government’s desire to alter the Endangered Species Act.

“We are losing our country,” said one demonstrator, Sara Harvey, 65. In the last few months, she said she had protested the federal job cuts led by Elon Musk and joined the nationwide protests on April 5.

“I’m worried for my grandchildren,” she said. “I do it for them.”

In Cincinnati, thousands of people marched peacefully through downtown. Aftab Pureval, the mayor, led the crowd in a chant of “vote them out” and denounced the Trump administration for cutting federal workers, imposing tariffs and mismanaging the economy, saying that everything that working families need will become more expensive.

For some who attended, like Andrea Mallory, 35, a social worker, the event was akin to a group therapy session.

“This is good for us emotionally,” she said.

A celebration in Concord, Mass., to commemorate the 250th anniversary of the beginning of the American Revolution was not part of the organized network of protests, but some people took the occasion to draw parallels between then and now.

Conan Walter, 65, stood on the Old North Bridge holding a large poster scrawled with the words “Stop fascism now.”

“This celebration is about us getting out from under the King of England’s authoritarian rule,” Mr. Walter said. “That rule is trying to make a comeback today, and it’s important that people step up against that and meet the challenge.”

Still, not everyone in Concord was there to protest on Saturday. Deborah Bucknam, 78, an avid Trump supporter and lawyer from northern Vermont, said she felt shut out of the political conversation on Saturday morning. Ms. Bucknam came to Concord to honor American history, and she said political differences shouldn’t overshadow the milestone.

But she acknowledged that demonstrators were allowed to voice their dissent.

“Protests are part of the American experience,” she said. “We have a right to protest, but everyone has a right to protest.”

Robert Chiarito contributed reporting from Chicago; Lila Hempel-Edgers from Concord, Mass.; Mary Beth Gahan from Fort Worth; Nichole Manna from Jacksonville, Fla.; Nate Schweber from New York; and Kevin Williams from Cincinnati.