Missouri’s hard-to-enforce policy toward illegal immigrants is in the news again. The St. Joseph News-Press reports on the uphill battle to prevent illegal immigrants from working:

The governor is asking the commission to use a computer database administered through the Department of Homeland Security to ensure the legitimacy of workers at the site. He wants the commission to terminate contracts or tax credits with developers who knowingly allow contractors to use illegal workers.

Proponents of these regulations argue that there’s a cost in unemployment or lower wages when we allow illegal immigrants to work. Even if that’s true (and it’s not clear to me that it is), we should also consider the costs of identifying illegal immigrants and tracking them down.