Not at all. US law is pretty much in line with the national consensus on ethics (although perhaps not with your personal ethics). There are occasional discrepancies but when the national consensus undergoes major shifts the laws are usually revised accordingly within a few decades.

US people can't remotely agree on death penalty, marijuana usage, gun control, gay support, the church, abortion, war, trump or snowden. In a country where it's legal to openly give money to politicians, spy on all citizens and by pass habeas corpus.

I really doubt your statement.

So you agree with me that there are no clear universal ethical standards in some areas. You still haven't shown how Monsanto's actions were unethical.

Yes. Lying about harmful products you are selling is something unethical to my taste. At this point, I expect you to disagree.