"Migrant-hunting vigilantes," is how former Mexican president Vicente Fox described the Minuteman Civil Defense Corps (MCDC) when it began conducting "border actions" in April, 2005. But Chris Simcox, 45, the executive director of the MCDC, prefers to see his organization as a kind of benevolent patrol, or as he puts it: "a large neighborhood-watch group."

"We're not against immigrants," Simcox says. "We're against illegal immigration, which is a problem of national security." Simcox cofounded the MCDC in 2004, after patrolling the border between Arizona and Mexico for two years with an organization he founded called Civil Homeland Defense. These border patrols were first launched in response to the September 11th attacks: if the government cannot prevent immigrants from crossing the border, he wondered, how will it manage to stop well-planned terrorists?

Armed with little more than binoculars, cell phones, and water, the MCDC are hardly outfitted for law enforcement. When they come across illegal immigrants, the official MCDC policy is to call the Border Patrol and wait. Simcox says that most of what they end up doing is search and rescue. "We've given out thousands of gallons of water to illegals," he says. "We've contacted emergency services, gotten people medical attention."

Even if the MCDC is saving lives, as it claims, its mission remains wildly controversial. For immigrant-rights groups like The National Council of La Raza and the Immigrant Solidarity Network, the MCDC is little more than a hate group peddling nativism. The Southern Poverty Law Center calls Simcox "a celebrity extremist." Despite these condemnations, Simcox and the publicity-savvy MCDC have become important enough players in the immigration debate that they can't be written off simply by denouncing their motives. And Simcox says that accusations of racism have started to get old. "What we're fighting has nothing to do with race-it's about rule of law." He even quotes Martin Luther King Jr.: "I judge a person not by the color of their skin but the content of their character." But only, it would seem, if that character has a green card.