By Maddie Hanna

Just how does FedEx track millions of packages -- and can the same technology be adapted, as Gov. Christie said over the weekend, to track visitors who overstay their visas?

"If FedEx can do it, why can't we use the same technology to do it?" Christie, a Republican presidential candidate, told an interviewer over the weekend as he joined the debate over border controls.

FedEx declined to comment on Monday on Christie's remarks, but a former executive at the company described its tracking system as commonplace. "It's all based on bar-code scanning, not particularly different from what you might find in a grocery store," said Roger Frock, author of Changing How the World Does Business: FedEx's Incredible Journey to Success -- The Inside Story.

"You'd have to put a tracking code on that individual, or track some part of that individual," Frock said.

Doris Meissner, commissioner of the former Immigration and Naturalization Service under President Bill Clinton, noted the same impediment.

"There are a couple issues with" a FedEx approach, Meissner said. "You really would have to deal with . . . getting a bar code onto people." The Democratic National Committee hammered Christie over the comments Monday, accusing him of "dehumanizing our nation's immigrants."

Asked Monday how the governor believed FedEx's technology could be applied to people, his campaign spokeswoman, Samantha Smith, referred The Inquirer to his remarks on Fox News Sunday. Smith is the daughter of FedEx's founder, Fred Smith.

"Let's use the same type of technology to make sure that 40 percent of the 11 million people here illegally don't overstay their visas," Christie said on the program, a day after touting the idea at a campaign event in New Hampshire.

During the exchange, host Chris Wallace asked how Christie would be able to know if someone overstayed, noting that "they don't have a number, you know, a label on their wrist." Christie said, "No, we can do it. And we should bring in the folks from FedEx to use the technology to be able to do it."

He added, "I don't mean people are packages, so let's not be ridiculous."

While Congress mandated an immigration entry and exit system in 1996, "there isn't yet a fully developed exit system because it's extremely difficult to do," said Meissner, director of the Washington-based Migration Policy Institute's U.S. Immigration Program.

One problem with tracking the exits of visa holders: People don't always leave the country where they arrived, she said. Other issues, she said, include getting the cooperation of airlines in reporting a visa-holder's departure.

"It is a legitimate issue," Meissner said. But she said the most effective way to stop people from overstaying visas would be to discourage employers from hiring them.

Christie's proposal is the latest addition to the immigration debate in the crowded Republican field, with Donald Trump dominating headlines with calls to build a "beautiful" wall along the southern border.

Wisconsin Gov. Scott Walker has suggested the country may also need a wall on the border with Canada. "That is a legitimate issue for us to look at," he said Sunday on NBC's Meet the Press.

Christie isn't the first Republican candidate to draw inspiration on immigration from the package-tracking industry.

Former Texas Gov. Rick Perry, according to the Des Moines Register, said at an Iowa event in March that "if UPS can track a box all around the world and know exactly where it is 24/7, we can give people a card and allow them in here and say that when you hit your visa limit . . . we're going to let you know: Your time's up."

(c)2015 The Philadelphia Inquirer