[antonymoose]

Depending on the circumstances, the mood of a Federal agent, and of a prosecutor it could be charged either civilly or criminally. The sibling comment explains this better than I could.

Stepping past the direct offense of being here, one must ask how are they supporting themselves financially? Assuming they are workers, they’re either not paying taxes (a crime) or stealing the identity of a citizen in order to fool an employer. Now they are at least paying taxes, but they’ve victimized a lawful resident or Citizen. This is far from a victimless crime, it took my mother two years to fully clear her name after this occurred to her identity. The IRS and credit agencies are not very understanding.