Reggie Walton, the federal judge who sentenced a former vice presidential aide, I. Lewis Libby, to prison, learned to respect authority when his fed-up father confronted him over his teenage brushes with the law.

“I was lifting weights, and I raised my fists,” Judge Walton said. “I thought I could handle him.” His father grabbed him by the collar, demanding that he obey and turn himself around.

He did, and now he’s the one in authority, known for tough sentences and stern lectures for the powerful and nonpowerful alike. Maybe too tough, some usually law-and-order conservatives have said. They are criticizing him over the 2 1/2 year prison term he ordered Libby to serve for obstructing an investigation into the leak of a Central Intelligence Agency operative’s identity.

Those who know Judge Walton, 58, say they weren’t surprised at the sentence. “Reggie has a concern for the system” and understands the importance of being impartial, said a former deputy U.S. attorney general, Eric Holder. Judge Walton’s attitude, he said, is: “If you do the crime, be prepared to do the time.”

The sentence was “grossly excessive,” Mayor Giuliani, a former federal prosecutor, said during a candidate debate in New Hampshire on June 5, hours after the sentencing. William Kristol, editor of the Weekly Standard magazine, called the judge’s decision “unfair and vindictive.”

Even some of Judge Walton’s admirers say they have reservations. “I think he’s a great judge, but the sentence Libby got, it was a little farther than I would have gone,” said Mr. Holder, the no. 2 Justice Department official during President Clinton’s administration and a fellow local District of Columbia court judge with Judge Walton during the 1980s.

Libby has also drawn support from a group of legal scholars including a former U.S. appeals court judge, Robert Bork, and Harvard law professor Alan Dershowitz, who filed a brief backing one of his arguments in seeking to stay out of prison during his appeal.

A federal appeals court will now decide whether Judge Walton went too far in ordering Libby, 56, incarcerated while he appeals. Libby, who was Vice President Cheney’s chief of staff, may be behind bars within weeks if the three-judge court rules against him.

“I believe in punishment,” Judge Walton was quoted as saying in the 1994 book “Black Judges on Justice,” by Linn Washington. “I believe when people do something wrong, they should be punished.”

In an interview last week in his federal court chambers in Washington, Judge Walton said it’s important to get sentences right in order to maintain the public’s confidence in the judiciary.

He cited the fact that mandated sentences are tougher for offenses involving crack cocaine than for powder cocaine. While “from a pharmaceutical perspective, crack cocaine is no more addictive than powder,” federal law requires sentences 100 times harsher for crack-related offenses, he said. “This undermines faith in the system,” he said.

Mr. Holder said that during Judge Walton’s time on the D.C. bench, he was concerned both by the devastation caused to black communities by the drugs and by the long prison sentences given to offenders.

Judge Walton’s own youthful scrapes with the law were minor, mainly fighting, the judge said. “My saving grace was the fact that I had good parents” at home in Donora, Pa., he said.

He attended a summer program at Howard University Law School in Washington in 1971, graduating near the top of his class and earning a scholarship to American University’s Washington College of Law in the nation’s capital, where he graduated in 1974. After serving as a federal prosecutor, he was appointed by President Reagan to the D.C. court in 1981, at age 32.

In 1989, Judge Walton joined President George H.W. Bush’s administration as assistant to drug czar William Bennett. He found the experience “frustrating,” partly because not enough money was available for education and prevention programs, the judge said in the book. Judge Walton returned to the D.C. court in 1991, and a decade later President Bush named him to the federal bench.

“It is satisfying to be a judge,” Judge Walton said in the interview.