I work in an area overun with illegals.

Until a few years ago if we booked an illegal imigrant into jail the INS would put a hold on them. They would interview the illegal and upon release from jail, deport him.  For some reason they changed that policy and now they will only put a hold on them if they are arrested for a felony.  If they are convicted of the felony they still get deported.  But if they plead down to a misdemanor (say arrested for ADW but plead down to simple assualt) INS lifts the hold. Same if the DA files a misdemanor charge instead of the felony they were booked to. (Booked for spousal abuse which is a felony thats often prosecuted as a misdi).

BP will also not accept intoxicated illegals.  So one way to avoid deportation, or "voluntary" return to Mexico is stay piss drunk 24/7. In the rare instances that we can get BP to make the hour drive north from the checkpoint they will take the sober illegals, but cant/wont take the drunk ones.