Quite the hullabaloo has greeted news of an exchange between Mayor Giuliani and CNN chat-show talker Glenn Beck. On Friday, Mr. Giuliani appeared as a guest on Mr. Beck’s show, and the topic was illegal immigration. Mr. Beck asked Mr. Giuliani if illegal immigration is a crime, and Mr. Giuliani had a simple answer: No. Immediately, a spokesman for the former governor of Massachusetts, Mitt Romney, charged that Mr. Giuliani was showing a “lack of interest in making enforcement of our nation’s immigration laws a priority” and said that this “puts him at odds with those who want to secure our borders and end illegal immigration.” Other immigration restrictionists piled on online and on the radio.

Putting aside for the moment Mr. Romney’s hypocrisy on this issue — Massachusetts had four official “sanctuary cities” under his tenure, and he never lifted a finger against them — there’s another reason this exchange is less than damning of Mr. Giuliani: He’s right on the facts. “Isn’t illegal immigration a crime in and of itself?” Mr. Beck asked the former mayor. “No,” Mr. Giuliani answered. “I know that’s very hard for people to understand, but it’s not a federal crime. … I was U.S. attorney in the southern district of New York. So believe me, I know this. In fact, when you throw an immigrant out of the country, it’s not a criminal proceeding. It’s a civil proceeding.”

It’s an important point. While “illegal immigration,” as a phrase, might imply a crime, being in America without authorization is a civil offense, not a criminal one. As the Congressional Research Service report titled “Immigration Enforcement Within the United States” put it in 2006: “Being illegally present in the U.S. has always been a civil, not criminal, violation of the [Immigration and Nationality Act], and subsequent deportation and associated administrative processes are civil Proceedings.” Thus, the penalty for immigrating illegally is deportation, not prison. Smuggling immigrants, or returning to the United States after having been deported, on the other hand, is a crime.

What’s more, in the interview, Mr. Giuliani showed a depth of understanding of this issue that has been all too absent among the candidates — not to mention the editorial writers. He was asked whether — if not currently a crime — illegal immigration should be a crime. And, again, he had the right answer: “No, it shouldn’t be because the government wouldn’t be able to prosecute it. We couldn’t prosecute 12 million people. We have only 2 million people in jail right now for all the crimes that are committed in the country, 2.5 million. If you were to make it a crime, you would have to take the resources of the criminal justice system and increase it by about 6.”

“So what’s your solution?” Mr. Beck asked. “My solution is close the border to illegal immigration,” Mr. Giuliani answered. He could have argued to increase the number of immigrants we’re willing to take or to move faster to legalize those who want to come in, either one or both of which would have been our preference, even if hard to argue in the current political context. If the former mayor is vulnerable to attacks from the immigration restrictionists, it’s because he’s gone too far in trying to align himself rhetorically with the modern-day know-nothings.

But Mr. Giuliani gave a glimpse in his talk with Mr. Beck of the mayor who understood the benefits even undocumented immigrants bring to this city and this country. We interpret his remarks as laying the ground for him to back away from any party faction that treats undocumented immigrants as criminals — or even invaders. He’s supported the building of a wall between America and Mexico; he’s called for biometric ID cards to track all foreigners, and he’s cut radio ads emphasizing crimes committed by illegal aliens. But making it clear that illegal immigration itself is not a crime is at least a start. His next step can be to take a stand against the immigrant-haters and in favor of America’s role as a beacon of growth — which is hope — in the world.