Can International Laws Be Used In The Us?

[Markel]

Question is much too broad and general to be responded to. Specifically, what International laws are being referred to.
As a general statement, it can be said that only US statutory law (federal and state) applies when within the US, just as citizens of the US are subject to the laws of whatever foreign nations they happen to be in.
So-called "international laws" such as The Geneva Convention - Maritime Law - etc - etc, apply to all nations, including the US, which are signatories to those laws.