No. When two other people who know the person offer such comments, a reasonable listener can infer that the subject of the comments is not legal. This would precisely translate in the case of drugs:
COP: By the way, do you have any illegal drugs in the car? Anything you want to tell me now?
SUSPECT 1: I’m not going to answer that.
SUSPECT 2: Mano, dile que tenemos nada! (Bro, tell him we don’t have anything!)
SUSPECT 3 (to SUSPECT 2): Callate la boca! Pueden búsquedar! (Shut up! They can search!)
So now you want a scenario where:
[ul]
[li]No other crime has been committed[/li][li]An illegal has declined to answer whether he’s a citizen[/li][li]There are no parties other than the cop and the illegal present[/li][/ul]
The only scenario I can imagine under those circumstances would have to involve some rather far-fetched plain-sight documentary evidence:
COP: By the way, are you a citizen, sir, or a legal resident?
SUSPECT: I’m not going to answer that.
COP: I see what appears to be a Mexican passport in your left front shirt pocket.
SUSPECT: It’s not mine.
That would establish reasonable suspicion.
Note that, in contrast, the following exchange would not:
COP: By the way, are you a citizen, sir, or a legal resident?
SUSPECT: I’m not going to answer that.
COP: I see what appears to be a Mexican passport in your left front shirt pocket.
SUSPECT: (remains silent)