HR Employment Laws

Throughout chapter 3 of the book, we review many employment laws at the federal level. However, there are also similar CA laws and sometimes local laws that we have to be aware of.
Which employment law (clarify if it is federal/state/local) do you feel is most complex or challenging?
Share what you know or have learned about the law (in regular words not legalese) and give an example of how you think it applies.
What other clarification do you hope to learn about this law?