Legal Question in Criminal Law in California

Because there is no standard definition of a "background check," it's anybody's guess whether it will come up. For government employers and the military, it will come up for sure. In a private database company search, maybe, maybe not. Because your brother's economic survival is at stake, if I were him I would lie like hell and say "no" on the form. For all anybody knows they might not look, they might not find out, or by the time they find out they might like his work and decide to keep him on anyway. He has nothing to lose.

Of course. Records are forever. However, he could seek to have juvenile records sealed, which would certainly help him, if successful. He'll need a local attorney to do so. If this is in SoCal courts, feel free to contact me.