Why?

Just to piss off internet libertards like you. No other reason. It's all about you.

The thing with US Federal law though is that treaties override constitutional laws. Laws Constitution Treaties. So any major unconstitutional idea that Has To Be Passed For Your Safety will be written and signed as a treaty with another country if it is too controversial for the public to accept.

Do you have a source supporting this claim?

I would love to see a citation for the claim that taconite tailings are "highly toxic".