The breakage of “norms” by President Trump has become a dominant theme of his critics. What a norm actually is when it comes to the presidency is now the subject of considerable academic research. But as the late Supreme Court Justice Potter Stewart said of pornography, we know it when we see it, and we saw it Wednesday.

Just hours after speaking to the nation about “heart” and “soul” in the face of humanitarian crisis, President Trump tweeted that he had ordered the Federal Emergency Management Agency to cut off aid to California’s wildfire recovery efforts unless state officials “get their act together, which is unlikely.”

He was presumably referring to the what he has called, without evidence, the state’s “gross mismanagement” of forests in California. The last time he ventured into this territory — wishing that California would do more “raking,” like Finland, people laughed, especially people in Finland, who had no idea what he was talking about.

After his tweet Wednesday, mirth was in short supply. California’s lethal wildfires, 8,500 of them, consumed nearly 1.9 million acres, killed at least 86 people, left thousands homeless and destroyed an entire town.

It’s conceivable Trump and FEMA would be breaking the law were they to follow through. Two law professors specializing in disaster assistance and the Stafford Act, which governs it, were unaware of any provision allowing the extreme measure Trump promised. The administration is on the losing end of dozens of important court cases that began just this way — including, most famously, one involving a tweet banning transgender people from the military.

Both, Robert Verchick of Loyola University New Orleans College of Law and Ernie Abbott, an adjunct at George Washington University Law School who practices at the firm of Baker Donelson, were certain that no president had ever made a comparable threat.

“It’s absolutely a violation of norms,” Verchick said. “And just to be perfectly clear, the norm of the federal government helping communities recovering from disasters is a norm that goes back into the 18th century. … It’s just shocking that a president would hold these suffering communities hostage in exchange for state forest management policies he knows nothing about.”

Said Abbott: “I’m not aware that any president has ever directed that no funds should be provided to a state. It’s absolutely not the norm to do this.”

That norm, now broken, could be considered a subcategory of a presidential norm lay people might just call “thinking.” We know that when we see it, too. A more elevated version came from Daphna Renan, who in the Harvard Law Review identified the norm of the “deliberative presidency.”

“The deliberative-presidency norm requires a considered, fact-informed judgment,” she wrote, a collective effort in which experts are consulted and meetings held before a president acts. In other words, a president is supposed to know what he’s talking about.

Trump’s first version of his tweet — later corrected — misspelled “Forest,” endowing it with two r’s. More significantly, as the Los Angeles Times wrote in an editorial, the threat had little to do with forest management and a lot to do with California’s new governor asking for more funding for forest management.

“Trump’s tweet is not only cruel and vindictive,” the Times wrote, “… it’s also incorrect. California is getting its act together. The state is putting up record levels of funding to reduce fire risk.”

It’s unclear whether FEMA officials were consulted about Trump’s proposed order. No one was home Wednesday to answer questions because of the government shutdown.