Reducing carbon emissions is a crucial goal. But that worthy end doesn't justify the Obama administration's legally dubious means to reach it. And Monday's Environmental Protection Agency order for draconian new carbon regulations again displayed the White House's disregard for the constitutional separation of powers.

Yes, we should lower the amount of carbon dioxide we put in the atmosphere. Even many who still stubbornly dispute the broad scientific consensus on man-made carbon emissions causing climate change concede that coal pollution is a health hazard.

However, high-stakes questions persist about how to accomplish this mission without wrecking the U.S. economy. And when our president ignores Congress on this critical problem, he deprives the nation's people of their legislative voice in its solution.

Thus, it's no surprise that numerous Democrats on this year's ballots are distancing themselves from the EPA edict. Scheduled to take effect a year from now, it would require existing coal plants to reduce CO2 emissions by up to 30 percent by 2030.

Some states - including ours - are even being subjected to an unfairly low baseline due to recent efforts to reduce coal emissions within their borders.

As Santee Cooper spokeswoman Mollie Gore said in Warren Wise's story in Tuesday's Post and Courier: "Santee Cooper has proactively cut emission levels 23 percent since 2005. Unfortunately, the EPA's proposed CO2 reduction counter starts at 2012."

Ms. Gore also warned that the new rules' expensive consequences wouldn't be confined to much higher home electricity bills: "If it stands, it will hurt South Carolina's economy by driving up power costs and driving away industry and the jobs they provide."

The Obama administration counters such objections with studies showing huge savings in health costs thanks to the cleaner air the regulations are projected to produce.

Of course, testing the limits of executive-branch power was a presidential tradition long before Mr. Obama was elected - and re-elected - to the White House.

Still, he is again reaching beyond his office's proper grasp. As Sens. John Barrasso, R-Wyo., and Heidi Heitkamp, D-N.D., wrote in a guest column in Tuesday's Wall Street Journal: "During the president's first term, Congress rejected, on a bipartisan basis, a national energy tax. These new regulations will in effect impose a national energy tax - but without the input of Americans or their representatives."

This latest presidential power grab extends a troubling pattern. The administration has routinely, and without legislative approval, invoked delays in the mandates of the Patient Protection and Affordable Care Act, fueling additional confusion about an already bewildering law.

And the president didn't give Congress 30 days' notice, as required by legislation he signed last year, that he was releasing five terror detainees from Guantanamo.

On Monday, CNN legal analyst Jeffrey Toobin, a self-described liberal, told CNN of that failure in last week's deal to win the freedom of U.S. Army Sgt. Bowe Bergdahl: "I think he clearly broke the law."

That's a serious allegation.

And regardless of Americans' CO2 views, they should be seriously concerned about President Obama's growing habit of governing by executive fiat.