Subject: Re: Trump makes demands
There is no presumption of innocence, if someone is arrested on suspicion of being an illegal?

I think you're thinking of a different situation.

This particular demand relates to people who are in the country illegally who are arrested by local authorities for a state crime, not on suspicion of being here illegally.

By construction, the population we're talking about are people who are here unlawfully. The concern underlying these sanctuary laws isn't based on people who are here lawfully not having an opportunity to prove it, but rather than anyone who is here unlawfully will face likely deportation if they are arrested by the local police - even if they are eventually found to have not committed any crimes (or only minor ones).