United States President Donald Trump’s appointee Neil Gorsuch on Monday showed himself to be a frequent and energetic questioner during US Supreme Court arguments in his first day hearing cases as a justice.

Gorsuch, whose confirmation to the lifetime job restored the court’s conservative majority, exhibited composure and confidence, sitting on the far right of the bench in the ornate courtroom, alongside Justice Sonia Sotomayor.

The first of the three one-hour arguments before the justices on Monday involved an employment dispute. Gorsuch grilled lawyer Christopher Landau, who represented a man claiming he was discriminated against by the US Census Bureau, over the fine points of a law governing civil service employees.

The justices, with the exception of the usually silent Clarence Thomas, are known for their aggressive questioning, and Gorsuch showed no qualms about jumping right in. “I apologize for taking up so much time,” the black-robed Gorsuch said, sitting back in his high-backed chair and smiling.

Chief Justice John Roberts welcomed Gorsuch to the court before oral arguments began. “Justice Gorsuch, we wish you a long and happy career in our common calling,” Roberts said. Gorsuch responded by thanking his new colleagues for their “warm welcome.”

In total, Gorsuch stepped in three times during the first one-hour argument, on each occasion asking a string of questions about the complicated federal law at issue. As he indicated during his Senate confirmation hearing last month, his line of inquiry focused on the text of the statute, an approach also embraced by the man he replaced on the court, Antonin Scalia, and other conservative jurists.

Citing a section of the Civil Service Reform Act, Gorsuch asked Landau where in the statute does it say federal district courts may hear cases involving both discrimination and civil service claims.

“Looking at the plain language of the statute, just help me with that,” Gorsuch said.