AMERICA’S judges are supposed to be above party politics and yet are often appointed by politicians and then asked to rule on disputes that can sway elections. On January 9th federal judges in North Carolina gave the state two weeks to redraw its congressional map. In a caustic ruling written by James Wynn, an appellate judge nominated by Barack Obama, the court found that the state’s current map—which let Republicans win ten of the state’s 13 districts with just 53% of the total overall vote—was “motivated by invidious partisan intent”, and violated the first and 14th Amendments. North Carolina vowed to appeal, which could see the case added to two other gerrymandering suits at the Supreme Court. The head of North Carolina’s Republican Party accused Mr Wynn of “waging a personal, partisan war on North Carolina Republicans.”

If Republicans get their way, Democrat-appointed judges like Mr Wynn will soon comprise a smaller share of the federal judiciary. No president has confirmed more federal appellate judges (12) in his first year than Donald Trump. He has also seen six federal district-court judges confirmed, and one Supreme Court justice, Neil Gorsuch. Another 47 nominees await confirmation; 102 more federal judgeships remain open for Mr Trump to fill. With two of the Supreme Court’s liberal justices, and its one unpredictable member (Anthony Kennedy) aged 79 or older, the president may get to name another justice, cementing the Court’s conservative bent.

Mr Trump’s tax reform, penchant for deregulation and foreign-policy direction could all be reversed by the next president. But because federal judges serve for life, the largely young conservatives whom Mr Trump has placed on the bench will have an impact on American life and law that long outlasts his administration.

The federal judiciary is organised into 12 regional circuits and the nine-member Supreme Court. Around 400,000 cases are filed yearly in the federal system, which has around 1,700 judges. Each of these circuits has several district courts (there are 94 in all), which hear civil and criminal federal cases, and one appellate court (there are 13: one for each circuit and the appellate court for the federal circuit), which hears appeals against decisions made by federal district courts and agencies. Because the Supreme Court hears so few cases, federal appellate courts define most contested matters of federal law.

Every president leaves his mark on the federal bench, but Mr Trump’s will be larger than most, for two reasons. First, Senate Republicans confirmed fewer judges in Barack Obama’s last two years (22) than in any two-year period since 1951-52. Mr Obama left office with 107 federal judgeships still vacant—including Mr Gorsuch’s seat, held open because Senate Republicans refused to give Merrick Garland, Mr Obama’s nominee, a hearing. This was more than twice the number George W. Bush had at his presidency’s end. Second, in 2013 Senate Democrats eliminated the filibuster for lower-court nominees, which means judges can be confirmed with a simple majority vote, rather than the 60 required to break a filibuster. For many conservatives, this opportunity alone—rather than fear of letting Hillary Clinton exploit it—justified their support for Mr Trump.

He has not disappointed. The dithering and incompetence that have defined much of his tenure have been absent from his judicial-selection process. Some argue that the administration and Senate are pushing too many nominees through too quickly, but that is their prerogative: senators can slow the process if they feel steamrollered. Mr Trump has nominated orthodox conservatives whom the Republican-controlled Senate has happily confirmed.

During his campaign, Mr Trump promised that the judges he nominated would be “all picked by the Federalist Society”, America’s leading organisation of conservative and libertarian lawyers. Many of his nominees have ties to the group, as do Mr Gorsuch and Don McGahn, the president’s counsel. Mr McGahn told a Federalist Society gathering in November that the administration wanted to nominate “strong and smart judges…committed originalists and textualists [who] possess the fortitude to enforce the rule of law”. Mr Trump’s nominees, he crowed, “all have paper trails…there is nothing unknown about them.”

That list of qualities contains subtle digs at the two types of judges conservatives want to avoid. The first, embodied by David Souter, whom George H.W. Bush appointed, is the nominee with a thin record on constitutional issues who turns liberal on the bench. John Roberts, the current chief justice, exemplifies the second type: many conservatives deride him as a squishy institutionalist who caved in to public pressure when he twice voted to uphold the Affordable Care Act.

The maturing of the conservative legal movement, which was in its infancy when Mr Bush picked Mr Souter in 1990, and the strength of its pipeline and networks, has made wild-card nominees less likely, particularly under Mr Trump, who appears happy to be guided by the “Federalist people”. That does not mean, of course, that presidents know how judges will vote on each issue for ever. But Republican judicial nominees share a legal philosophy that is sceptical of executive and federal power and inclined towards “originalism”, which interprets the constitution’s meaning narrowly, as it would have been understood when it was written.

Republicans like originalists for various reasons. Social conservatives believe liberal justices invent constitutional justifications for socially progressive rulings such as those on abortion and gay marriage, while business types appreciate originalists’ scepticism of government regulation. Conservative judges view originalism as an essential bulwark against the judicial and presidential usurpation of legislative powers. Liberals believe such a philosophy hinders social progress. They will have ample opportunity to test that theory: a federal judiciary stocked with originalist judges will be hostile to an ambitious federal government. That suits Republicans well, but could frustrate Democrats for decades to come.