Immigration and Customs Enforcement (ICE) officials do sometimes make mistakes. One United States citizen was deported to Mexico because he was misidentified. It appears that he could not participate in his own defense because he suffered from a number of psychiatric and cognitive disabilities.
This individual was deported though he had never been to Mexico, was not of Mexican heritage, and did not speak Spanish. Prior to the deportation, he was detained for 51 days and placed in a position of defending himself without having an immigration attorney available to represent him. Only after an attorney became involved after being retained by the man's family was he then allowed to return to the United States.
ICE is not sure how often these sorts of matters occur. Mexico is right next door to California and yet communications across the borders concerning immigration remains almost non-existent. And because of mistaken identities and the failure of ICE to appoint an attorney for these individuals, this sort of problem is likely more common than one would suspect.
Individuals facing deportation hearings are the ones most in need of the services of attorneys. Even if those facing deportation are not suffering from mental illness, they often do not understand the nature of the proceedings being brought against them.
Wrongful deportations are costly for everyone. The above mentioned individual was left homeless, forced to wander through countries that he had no familiarity with and even at one point end up in a Honduran jail. It ultimately cost taxpayers tens of thousands of dollars to unnecessarily detain, deport this person, and eventually have him returned to the United States.
Source: ACLU, "Yes, the U.S. Wrongfully Deports Its Own Citizens," by Esha Bhandari, April 25, 2013