Samuel Alito’s inclinations have not been hard to discern lately. At the Supreme Court hearing on birthright citizenship earlier this month, legal experts identified him without hesitation as the justice likeliest to side with President Trump. “What we’re dealing with here is something that was basically unknown at the time the Fourteenth Amendment was adopted, which is illegal immigration,” Alito said. The comment hinted at a desire to sidestep the original understanding of the amendment, which, his fellow justices suggested, was that people born on American soil are U.S. citizens.Five months earlier, at a hearing on tariffs, even Alito’s erstwhile admirers at the National Review objected when Alito started referencing other statutes, not cited by Trump, as justifications for the president’s orders. The conservative outlet slapped back that “it is not the Court’s job to opine on powers the president has not invoked”—a notable rebuke from a publication that Alito read avidly as a young man.In nominating Alito on Halloween 2005, a sanguine President George W. Bush declared, “He understands that judges are to interpret the laws, not to impose their preferences or priorities on the people.” Alito’s more recent willingness to telegraph his preferences has coincided with more gruffness and edgier assertions in his interviews and speeches. Perhaps the justice is getting something off his chest; bluntness might be his protest against the straitjacketed propriety long expected of Supreme Court justices. Perhaps it is his response to the harassment, up to and including death threats, that justices face.But Alito’s trajectory also underscores something else: For all the justices’ honorable intentions and their promises to judge cases impartially, the fundamental dynamics of today’s ever more polarized Court are pushing them in a much different direction.[Sarah Isgur: What the Roberts Court is actually trying to accomplish]The notion of judicial neutrality wasn’t a pose for many conservatives. They believed in judicial restraint, in which judges refrain from allowing personal predilections to influence their decision making. Now, however, few see Alito as the same man who said, at the time of his nomination, “Good judges are always open to the possibility of changing their minds based on the next brief that they read or the next argument that is made by an attorney.”The libertarian legal analyst Andrew Napolitano, a retired judge who was Alito’s classmate at Princeton, told me that his friend’s Court decisions reflect his conservatism more than any other theory of jurisprudence. “Sam is not an originalist,” Napolitano said. “Sam is a conservative person who wants a conservative outcome.” Napolitano went on, “There’s nothing wrong with that in the Court in which he sits, because it’s a Court of last resort. If he was on the Third Circuit behaving that way, he’d get reversed a lot. But where he sits, he has the privilege of doing that.”Alito’s approach reflects a fissure in the conservative legal movement as it deals with Trump’s unusual assertions of power. The conservative justices may prefer Trump’s outcomes, but his methods challenge the system of checks and balances that they’ve sworn to uphold. A legal movement built on strict rejection of politics must pass judgment on a president who shares their same inclinations. Having decried and then overruled what they perceived as activist liberal precedents, judicial conservatives must confront the prospect of excesses of their own.How Alito and his ideological allies handle themselves, and the ground rules they lay down, will have implications well beyond Federal Reserve officials, U.S.-born children of immigrants, or any other current-day litigants. They will shape the contours of the American system for the foreseeable future.On the wall of Bush’s presidential library, in Dallas, is a large photo of Alito taking the oath of office, beneath which is a quote that begins: “A judge can’t have any agenda.” Alito goes on, “The judge’s only obligation—and it’s a solemn obligation—is to the rule of law. And that means that in every single case, the judge has to do what the law requires.”In the photo, Alito has the look of a man attaining his destiny. Like many leaders of the conservative legal movement, Alito came out of the post–World War II middle class. His Italian-born father and grandparents, who had faced down poverty and prejudice, preached about the transformative power of America. The patriotic ethos of Cold War–era public schools reinforced his sense of American ideals. American freedom was the antidote to the icy grip of totalitarianism, whether from Nazis or Communists.When he journeyed the 12 miles from his Mercerville, New Jersey, home to Princeton University, he epitomized the new meritocracy: European immigrants’ sons, many of them Catholic. But his was the last all-male class to enter Princeton, and jarring social changes followed. The rapid liberalization of the campus collided with President Richard Nixon’s incursion into Cambodia. Violent protests followed, including a bombing of the university’s ROTC headquarters.As a ROTC student, Alito was unfairly cast as a symbol of the military establishment that many classmates disdained. His disagreement with others of his generation was a notable lesson of his Princeton years. Describing this time at his Supreme Court confirmation hearing, Alito recalled, “I saw some very smart people and very privileged people behaving irresponsibly.” His sense of swimming against the currents continued at Yale Law School, where he was a student when the Roe v. Wade decision came down.Eventually, Alito found a more congenial home in the Reagan administration, where he was part of Attorney General Ed Meese’s senior staff and started on the path to the Supreme Court. Still, that administration’s legal calling card was restraint, not activism. The issue with Roe wasn’t that it allowed abortions; it was that judges, not elected representatives, had decided the matter. When Reagan himself addressed the nascent Federalist Society, he cast its mission as restoring a balance of power. “You are returning the values and concepts of law as our Founders understood them to scholarly dialogue, and through that dialogue to our legal institutions,” he said.Parts of Alito’s early record transcended factional politics. Serving as U.S. attorney for New Jersey in the late 1980s, he won bipartisan praise for his tenure. In 1990, the Senate unanimously confirmed his nomination to the Third Circuit Court of Appeals with the strong endorsement of his Democratic home-state senators, Bill Bradley and Frank Lautenberg.Over the next 15 years, Alito amassed a conservative record. By the time of his Supreme Court nomination, many believed the conservative legal movement was synonymous with the anti-abortion movement. A successful nominee therefore had to make a show of independence, and plausibly endorse principles of neutral constitutional interpretation.The shy, bookish, soft-spoken Alito projected the image of a perpetual student, albeit one who was a “conservative by temperament,” as The New York Times summed him up. By 2005, the Senate was in the grip of the bipartisan Gang of 14, who enforced a compromise that filibusters could be used to block Supreme Court nominations only in extraordinary circumstances, such as when a nominee expresses obvious bias.Alito and his supporters worked hard to refute any suggestion of partisanship. “The Sam Alito that I have sat with for 15 years is no ideologue,” Edward Becker, the longtime chief judge of the Third Circuit, testified at the time. “He is not a movement person. He is a real judge deciding each case on the facts and the law, not his personal views, whatever they may be.” More than four dozen of Alito’s former clerks signed a petition stating that it “never once appeared to us that Judge Alito had pre-judged a case or ruled based on political ideology.”Privately, Alito received encouragement from Justice Ruth Bader Ginsburg, a liberal hero. “A colleague of excellent judgment, Ed Becker, tells me that you are the very best,” Ginsburg wrote to Alito in a personal note, which I found among Becker’s papers at Yale. “I wish you well in the trying days ahead.”When Senate Democrats, led by Ted Kennedy, tried to hammer Alito for having belonged to a group of ultraconservative Princeton alumni, the nominee acknowledged having once claimed to be a supporter, but he pointedly rejected the group’s resistance to women and minority students. Alito’s humble, low-key approach was measured against Kennedy’s florid interrogations, a contrast that gained resonance after Alito’s wife, Martha-Ann, collapsed in tears at the hearing. The next morning, a chyron on NBC’s Today Show asked, DEMOCRATS GONE TOO FAR?Alito came out a winner, but still embittered. Years later, he would recount his miseries of late 2005 and early 2006, and he would not be alone among his judicial colleagues in dwelling on past slights.The confirmation process itself bears much of the responsibility for the Court’s jolt toward partisanship. As Ginsburg’s note attested, Senate confirmation hearings strike terror in cosseted jurists. Especially after Robert Bork’s rejection in 1987, Supreme Court nominees became proxies for abortion rights, affirmative action, gun control, and other deeply divisive issues. They quickly absorbed the reality that one party would do anything—scrutinizing their school records, dating history, personal finances—to defeat them, while the other would steadfastly defend them. Knowing who was with them and who was against them when their professional life was on the line generated a sense of gratitude and obligation where none existed before.Both Alitos felt deeply bruised. Eighteen years later, Martha-Ann Alito would be recorded expressing her still-raw anger over a Washington Post column that critiqued her wardrobe. “I think he responded to the culture of Washington by becoming defensive,” Bush’s top adviser, Karl Rove, told me, referring to Alito. “It’s an ugly thing to confront. It was difficult for him and his wife to deal with.”Alito’s early years on the Court were relatively quiet, as he kept a low public profile while acclimatizing himself to his new role. But the conservatism of his jurisprudence quickly became apparent. His first sign of public testiness came after President Obama’s condemnation of the Court’s Citizens United v. FEC decision at the 2010 State of the Union address. “Not true,” Alito, seated in the audience, appeared to murmur in response. Over time, he has become known for bluntly questioning litigators, candidly speaking out at conservative legal conferences, and advancing expansive legal protections for the free exercise of religion, a cause that he also trumpets in public.“If we are honest about what is really going on here, it’s not about ensuring that same-sex couples in Philadelphia have the opportunity to be foster parents,” he lectured an attorney several years ago. “It’s the fact the city can’t stand the message that Catholic Social Services and the archdiocese are sending by continuing to adhere to the old-fashioned view about marriage. Isn’t that the case?”In 2020, he raised eyebrows at a Federalist Society convention by angrily condemning efforts to keep judges from attending such conferences. In the same speech, he criticized the 1905 legal precedent that underlay many COVID-era restrictions—something many saw as egging on his fellow conservatives to mount legal attacks on social distancing. These actions weren’t unprecedented: Ginsburg sometimes made political comments and moved in liberal legal circles.More unusual was the revelation of Alito’s wife flying an upside-down American flag—a symbol associated at the time with pro-Trump “Stop the Steal” activists—while the Court was weighing challenges to the 2020 election. The contrast between the bookish judge, lauded during his confirmation for his reverence of legal precedents, and the agitated, outspoken figure of recent years was especially noticeable to old friends and supporters.“I listen to a lot of Supreme Court arguments, and sometimes I am shocked at the tone and nastiness of some of his questions,” another friend of Alito’s from Princeton, who requested anonymity to speak candidly, told me. “I just can’t believe that’s my Sam Alito. But obviously, my Sam Alito at the time was holding back, or he’s evolved, or some of both.”A changed man exemplified a changed Court. Alito’s opinion in Dobbs v. Jackson Women’s Health Organization, which overturned Roe, was followed by Court-ordered curbs on affirmative action and gun control, and a decision allowing parents of public-school children to keep them out of lessons about books that have LGBTQ characters.Meanwhile, the six conservative justices banded together to construct a wall of immunity around Trump. For his part, Alito saw greater danger in overreach by local prosecutors than in legal wrongdoing by presidents, suggesting during oral arguments that “bitter political opponents” might hound former officeholders into their retirement years. Seemingly, the brakes on executive authority were off.Four decades ago, the American Bar Association was the prime source of vetting for nominees, and those who earned a “well qualified” rating were rewarded for their legal acumen, absent any politics. Collegiality reigned. Ginsburg fondly recalled her days on the D.C. Circuit Court of Appeals, suppressing laughter over her fellow judge Antonin Scalia’s jokes.But social interaction among judges appointed by different parties has waned. The Federalist Society and its liberal cousin, the American Constitution Society, serve as guardians of the separate ecosystems in which the jurists live, socialize, and build their reputations.Among Alito’s closest friends are his former clerks, a natural bond. But almost all were drawn from the chambers of a small number of highly conservative lower-court judges. When he wants to get a message out, he turns to sympathetic platforms such as The Wall Street Journal’s opinion pages and The American Spectator.[Read: John Roberts’s dream is finally coming true]In an interview with a Journal opinion writer, Alito said, “I marvel at all the nonsense that has been written about me.” He acknowledged that the traditional expectation has been for judges to “be mute” and let the legal establishment defend them, but no such defense was forthcoming: “And so at a certain point I’ve said to myself, nobody else is going to do this, so I have to defend myself.” His implication, perhaps subconscious, is that occasional flashes of partisanship are a form of self-defense.Alito’s own feeling of beleaguerment may have spilled over into sympathy for Trump’s. In the Court’s “shadow docket” of emergency rulings on Trump’s efforts to stretch his executive power, the president has largely prevailed. On the rare occasions when conservative colleagues have joined with liberals to rein in Trump, Alito has held firm.But as the Court prepares to rule on birthright citizenship and the president’s control over the Federal Reserve—and potentially many more cases involving Trump’s executive power could come in the near future—not all of Alito’s fellow conservatives have been prone to reflexive partisanship. Justices John Roberts, Amy Coney Barrett, Brett Kavanaugh, and Neil Gorsuch have, at least in a few cases, seemed responsive to arguments about the need to restrict presidential authority. They seem to realize that their movement’s first principles call for strict fidelity to the Founders’ intricate system of checks and balances.Will Alito join them? Somewhere within him is the spirit of the patriotic teenager and the careful lower-court judge who rejected any notion of party loyalty or judicial agenda. Perhaps he can yet find the will to channel his earlier self.