Illegal aliens break the law when they enter the country. Ditto the employers who knowingly hire them. Both groups are guilty of crimes. Yet both are merely doing what rational individuals (if immoral) would do—because the U.S. government has chosen not to punish these crimes.
In Becker's model, criminals are rational individuals acting in their own self interest. The "cost" of crime to criminals consists of two parts. One is the income foregone by devoting time to criminal activity—the so-called "opportunity cost". For illegal aliens, like most criminals, this cost is very small. They are largely unskilled and uneducated; jobs in Mexico, if available at all, do not pay as well.
The second, and far larger, cost of crime to criminals is the time they expect to be incarcerated because of this activity. "Expected punishment" is not the same as the length of time a convicted criminal actually spends in prison. Most crimes never result in an arrest. Many of those arrested aren't prosecuted. Many convicts are paroled.
So expected punishment, from the perpetrator's point of view, is a probability—not a certainty.
Take burglary. There were 2,154,126 burglary offenses reported to law enforcement authorities in 2005, and 298,835 arrests for burglary that year – producing a de facto arrest rate of 13.9 percent. Of those arrested for this crime, 90 percent are usually prosecuted. Of those prosecuted 67 percent are convicted.
Bottom line: Only 8.4 percent of reported burglary offenses result in a conviction.
By comparison, there were an estimated 7,355,000 illegal aliens working in the U.S in 2005. (This figure, from the Pew Hispanic Center, is based on their overall population estimate of 11.5 million illegal aliens. Other studies put the illegal alien population as high as 20 million.) [The Size and Characteristics of the Unauthorized Migrant Population in the U.S. Estimates Based on the March 2005 Current Population Survey(PDF|HTML)]
A mere 251 illegal workers were arrested on the jobsite by U.S. Customs and Immigration Enforcement (ICE) agents in 2005. Of those arrested, 188, or 75 percent, were convicted for violating immigration laws. [Homeland Security, 2005 Yearbook of Immigration Statistics, November 2006. Table 37. PDF]
Bottom line: Only 0.003 percent of illegal alien workers can expect to be arrested.
Worksite arrests peaked at 17,554 in 1997, and then plummeted to 953 in 2000— the Clinton administration's last full year. Thus the downward spiral was underway well before 9/11. But it accelerated under George W. Bush. In 2004, there were just 159 worksite arrests—and only three (3!) employers fined.
It wasn't supposed to be this way.
The Immigration Reform and Control Act of 1986 granted the then-existing illegal alien population of three million plus green cards and a path to citizenship. But the obvious incentives for entry were to be removed, we were assured, by the enactment of strict sanctions against employers who knowingly hired illegal alien workers.
The key phrase here is "knowingly hired". IRCA required employers to demand documents establishing an alien's eligibility to work, but provided no easy way of ascertaining the legitimacy of those documents. A deluge of counterfeit social security cards enabled employers to wink knowingly at their new hires.
Immigrants aren't stupid. Neither are their employers. They come, they hire, because it is entirely rational for them to do so.
One estimate is that requiring employers to verify the status of workers could trigger a spontaneous exodus of about 2.5 million illegals over five years. [Jessica Vaughan, "Attrition through Enforcement: A Cost-Effective Way to Shrink the Illegal Population", CIS Backgrounder, April 2006.]
That, plus a border fence….