How Can You Tell Someone Is Illegal?

First off, I know I'm asking a lot of questions surrounded by here, but it's for school. Second, don't say "they're BROWN!" or whatever, you're not funny, and not artistic.

For my independent study about illegal immigration, I was thinking of doing my product as an awareness packet, that includes how to relay if someone if illegal, who to contact, ect. I need some more ideas to put contained by it, as well as how to tell someone is illegal.
Answers:   
my favorite way is to the home depot, sometimes you'll find a good size group. If yell "la migra" the illegals will rum close to crazy. Also, no drivers license, Social Security number, or english speaking skill. the canadians, are harder to spot, but they are part of the illegal culture. it takes a perceptive eye, and a good ear. Instead of asking for answers on here, why don't you ACTUALLY go into a LIBRARY and do some ACTUAL RESEARCH..
If they can't produce valid proof of Citizenship OR Valid Passport stamped with date of entry (for visitors) or next to appropriate visas to work in the US or green card.

There are already specific requirements for all American businesses to establish the eligibility of employees to work contained by the US and laws outlining the proper doucumentation required. Every employee must supply this proof.

I think enforcement of immigration tenet is the job of the authorities. Your everyday person is not equipped to assess the validity of documents and really have no right to go around demanding that people prove they are in the country legitimately.
The new arrivals are easiest to spot, in public they skulk around and avoid eye contact. After they are here awhile they get more confident and are not as jammy to spot..My opinion and experience! Just pull up in a black van,yelp green card and see who runs. Those would be illegals.
You can tell because they don't enjoy ID or a greencard. DON'T THE LIBERALS WILL SAY YOU'RE PROFILING.
I see not getting much oblige here from some of the ignorants that are answering like the other person said library best resource.
ask for their birth certificate?
i dont know
you cant tell through appearance so your gonna need to see their ssn i.d and other things

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