For anyone tempted to let sympathy over-rule common sense, please read the following from Newsweek (Yes, that's right, Newsweek):
As tough as the United States can be for workers who slip in from south of the border, Mexico is in a poor position to criticize. There's ample precedent in Mexico for just about everything the United States is—or isn't—doing.
U.S.-born kids may be split from illegal parents
Mexicans may hate the new U.S. plan to deploy 6,000 National Guard troops on the border, but five years ago they cheered President Vicente Fox for sending thousands of Mexican soldiers to crack down on their southern frontier.
Hispanic-rights groups are enraged over U.S. efforts to criminalize undocumented aliens—yet since 1974, sneaking into Mexico has been punishable by up to two years in prison.
Fox has spent the past five years urging the United States to upgrade the status of millions of illegals from Mexico. Meanwhile, his own government has given legal status to only 15,000 foreigners without papers.
Any why don’t they give these jobs to Mexicans?
"If you ask them, 'Why are you bringing in Guatemalans to work?' they say, 'You can't depend on Mexicans. They don't work hard; they're irresponsible'," says George Grayson, a political scientist specializing in Mexico at the College of William & Mary. "The truth is, you can pay [the guest workers] a pittance. And if they cause the slightest disturbance, you can send them back to Guatemala."