Which law establishes criminal and civil sanctions against employers who hire an individual knowing he or she is an unauthorized alien?

In 1986, the Immigration Reform and Control Act set these standards. This was passed to toughen the penalties against companies who were hiring large numbers of immigrants and using them for low-wage labor. In addition, the act reprieved a large number of currently-undocumented immigrants, but also denied them federal benefits.

The answer popular sovereignty.