The problem is not as much the rule of law as the law itself. As long as the child is a US citizen, there will probably be no problems - but I know of multiple kids who have fallen foul of the INS due to bureaucratic loopholes.

One specific case was an unaccompanied minor (Indian citizen) who had on a previous visit to the US failed to surrender the form I-94 at departure. This 14-year old was heading to spend the summer with an aunt in New Jersey, but was denied entry at JFK because the system showed him to be out-of-status. However, since the child was being subjected to expedited removal, they would not permit the aunt to take custody of the child - nor could they actually deport the child without a hearing since the underage child had no legal standing to sign a document consenting to a waiver of hearing. The child remained imprisoned in an INS detention center for 5 days until the aunt could obtain advance parole and accompany the child in deportation to India. The child is also now slapped with a statutory 10-year ban from visiting the United States.