Why isn't police certificate needed from home country when applying for AOS?

[steen]

I'm wondering why no police certificate from a home country is needed when applying for a adjustment of status, but is needed for some visas? I would think that it should be needed, but do they do their own criminal background check in the home country or has that already been done in order to get the initial visa coming into the US? It just doesn't make all sense to me why you don't have to send it in.

[immihelp]

Well, that is how it is. Laws are not always consistent.

They don't do any background check from home country for AOS applicants.