Gorsuch, the nominee President Donald Trump is betting on to be his Supreme Court tie-breaker, wrote a 2016 ruling permitting Hugo Rosario Gutierrez-Brizuela to stay in the U.S. and, his lawyer hopes, within a few years become a citizen.

“Without it we were done,” said Timothy Cook, the attorney. Had the decision gone the other way, Gutierrez-Brizuela would have been promptly deported, he said.

As Trump vows to fight all the way to the nation’s top court to preserve his temporary ban on travel from six mostly Muslim nations and immigration agents turn to more aggressive tactics on city streets, Gorsuch’s conservative credentials have been hailed as likely to swing the divided court in the president’s favor.

But as lawmakers scrutinize Gorsuch’s decade-long tenure on a federal appeals court for clues about how he might rule on hot-button issues such as abortion and gun control, his record shows that on immigration rights, he can’t be easily categorized.

Moreover, some experts and academics say Gorsuch’s criticism of executive overreach in the Gutierrez-Brizuela case and others could lead him to reach decisions at odds with the Republican president’s policies.