Did you not read any of the articles I posted on the Mexican Repatriation thread about the government often detaining and deporting American citizens? And you are okay with this?
What gives a cop "reasonable suspicion" that somebody is an illegal immigrant?
It seems to me you're looking at the wrong part of the system. Of course we should never deport an American citizen, anymore than we should wrongfully convict somebody of a crime. But, that doesn't mean cops shouldn't ask a question, detain, and investigate just as they would if they suspected me of being a bank robber.
Now, if ICE is wrongfully deporting people that the cops bring to their attention, then we need to address that issue with ICE and put in sufficient safeguards.
But, I see absolutely no reason why cops, our first line of defense, shouldn't be allowed to get the ball rolling.