Last month, the U.S. Supreme Court’s conservative supermajority made a decision that places residents of the nation’s most polluted state — Louisiana — in even greater jeopardy: It dumped the 40-year precedent known as the “Chevron deference.”

And Gov. Jeff Landry cheered.

Now, you may have heard this is just a story about legal theory. But it’s much more serious. It’s the latest example of how allowing money to be considered political speech is pushing the U.S. from democracy toward plutocracy.

The “Chevron deference” refers to the 1984 Supreme Court decision establishing the precedent that when the language in a regulation is imprecise or ambiguous, courts should defer to the expertise of the enforcing agency in any decision.

For example, if new research showed a chemical not listed in the original Clean Air Act was carcinogenic, the courts would defer to the expertise of the Environmental Protection Agency staff to regulate that new pollutant.

The court wisely decided jurists’ expertise is in law, not the minutia of the fields being regulated. That expertise, they ruled, resided with the agencies’ professional staffs.

For 40 years that decision survived hundreds of court challenges, most from businesses trying to avoid regulations costing them money.

The irony of this story is that the case establishing the precedent was a win for industry against an environmental group. But Chevron soon became a crucial lever for environmental protection because polluters never stopped trying to have it overturned.

They claimed unelected bureaucrats were making laws, a privilege the Constitution delegates only to Congress. Courts disagreed.

They screamed that decisions were made without public input. But every regulation must move through the Administrative Procedures Act, which requires public and congressional input along the way. Nothing is done in secret.

They yelled that the agencies had not considered the costs. However, the process also requires an agency to file a complete cost-benefit analysis.

So successive waves of federal judges appointed by both Republican and Democratic presidents respected the sound reasoning behind the precedent — until this Supreme Court said they were all wrong. It decided that judges are qualified to make expert decisions in the many fields they know little about.

The death of Chevron did not happen overnight. Anyone watching the conservative tide swamping the federal bench could not have been surprised.

The 1980s saw the growth of conservative think tanks funded by billionaires and industries determined to make federal courts more business-friendly — meaning conservative. Their first big payoff came in 2010 with the Citizens United decision ruling that a law limiting campaign contributions was unconstitutional because it violated free speech.

At that point the bedrock principles of democracy that “all men are equal” and “one person one vote” became obsolete. How can we claim every voter is equal at a time when almost 70% of the wealth in our nation is held by 10% of the population — and wealth determines how much political speech each of us has?

How do you think elections would turn out if all voters, candidates and parties were limited to, say, $100 on an election?

Instead, just one week after the court killed Chevron, we were treated to this obscene spectacle:

Gov. Jeff Landry, whose career has been bankrolled by billionaires, holding a news conference in front of a polluting chemical plant in Reserve announcing a lawsuit against the EPA.

The agency’s sin: A new rule that would force plants to dramatically reduce the levels of carcinogenic pollutants they pour into the lives of Louisiana citizens.

Now, imagine his response if the EPA acts on recent research showing Louisiana plants are emitting twice the permitted levels of highly carcinogenic ethylene oxide?

Whose speech will he hear and listen to? The people living next to that plant, or the billionaires?

It´s like expecting a judge to make an unbiased ruling in a case involving his wife.

Oh, wait …