It is a premise of national identification policy that requiring proof of lawful presence to get an ID, then requiring the use of that ID for many essential functions of life, would make it more difficult to be an illegal immigrant in the United States. The natural result of having a national ID and routine identity checks would be suppression of illegal immigration. The premise is undoubtedly true.

The question is how much influence it would have on illegal immigrants’ decision whether to come to, or remain in, this country. And how much it would cause illegal immigrants to take other steps, such as avoidance of ID checks?

A recent article in the Arizona Republic illustrates that leaving the country isn’t the obvious step for illegal immigrants faced with the lawful presence requirement. “Illegal Immigrants Flocking to 3 States to Obtain Identification” tells the story of how illegal immigrant Carlos Hernandez moved his family to Washington state after the passage of S.B. 1070 in Arizona. The story is illustrated with a picture of Hernandez watching his 2‑year-old daughter play on a slide near their apartment in Burien, Washington.

“Hernandez said he knows other illegal immigrants who considered New Mexico because of the ease of getting a license. But he and others thought Washington would be safer.”

One inference from the story is that states with “weak” licensing requirements should tighten things up. But would Hernandez’ young daughter have better prospects if he moved the family to Puebla, Mexico, or would she be better off living in the United States with a father who acquired a false U.S. identification? In many cases, a family man like Hernandez will take the risk of acquiring and using false ID to provide his daughter the stable environment and opportunities the United States has to offer.

A national ID system, and background checks instituted for access to work, housing, and financial services, would suppress illegal immigration some, but it would also drive greater identity fraud and corruption.

The next question is how much inconvenience and tracking the natural-born and naturalized citizens of the country should suffer in order to achieve the marginal gains of presssuring illegal immigrants this way.

On balance, the gains are not worth the costs—especially when the “gains” include making life worse for Carlos Hernandez’ young daughter.