>>>It is now (and has been for decades), in most states in America,
>>>completely legal for a law enforcement officer to randomly set up
>>>a road block for the sole purpose of arbitrarily stopping citizens to
>>>search both their car and parts of their bodies on the off chance that
>>>the driver is possibly drunk.
>>
>>There are three types of law provisioned in our U.S. Constitution: Common, Equity and Admiralty. Common Law is common sense stuff (don't kill people). Equity is fairness law (what is most equitable). And Admiralty Law used to be the law of the sea, but it is business law, contract law, the things you voluntarily agree to.
>>
>>The reason why it is legal within the United States to stop people randomly is because they have agreed to it beforehand.
>
>The reason DUI checkpoints are allowed is because the Supreme Court
>decided in Michigan Department of State Police v. Sitz that the risk of drunk
>driving outweighs the 4th Amendment.

The Supreme Court has ruled on a Common Law condition which now supports it "officially, as a matter of course" which is, as you suggest, a usurping of authority not authorized that body by our Constitution. It was not necessary, however. It just makes it easier to point to a thing and say "See... right there it is."

UPDATE: I will add one more thing. This is a lot of what's happening with the legal system in America. Things have been changed
fundamentally, but without any outwardly apparent signs to the average person. We hear news snippets on this, that or the other thing, and they are a topic of water cooler conversation for some weeks or months, and then they are largely forgotten. For example, most people are unaffected in their daily life by the Military Commissions Act of 2006, or the Patriot Act, or any of the changes in U.S. policy which say its governmental agencies can now keep records on people who are not suspected of committing any crimes whatsoever for a period of up to five years (it used to be 180 days). However, these things now exist. They're part of our lives, even if we don't necessarily see it. It's like there's this infrastructure being developed, put into place, honed, flushed out, well employed, revised, extended, and solidified through reinforcement ... and for all practical purposes it's being done covertly because almost nothing is outwardly visible immediately to everyday citizens. It's also that there is no overt attention being drawn to it through its explicit use outside of "very occasionally." It is a fundamental "swapping out" of nearly everything we've believed in -- and were even taught in school -- since the early 1900s. I see it categorically as the infrastructure to bring about the end times as foretold in Ezekiel, Daniel, Matthew 24, Revelation, etc.

>The opinion perfectly demonstrates what the author is talking about when
>he says: We have spent the better part of the last century shredding our
>Constitution slowly, all under the guise of “public safety.”

I agree with this point. "The price of liberty is eternal vigilance." "We The People" have failed in this.