Dallas federal judge Ed Kinkeade presided over a September hearing that pitted Exxon Mobil against Massachusetts Attorney General Maura Healey.

The litigation also set 11 other state attorney generals against 22 of their peers from other states. The divisions among those AGs fell along the usually suspected lines—mostly South versus mostly North and mostly red versus mostly blue.

During the hearing the judge bemoaned the fact that political divisions seemed to define the legal stances on each side.

“I just hate this us and them thing, but it is what it is,” Kinkeade told Justin Anderson of Paul Weiss Rifkind Wharton & Garrison, who represented Exxon.

The Exxon Mobil case—pitting the emblematic blue state, Massachusetts, against the prototypical red state, Texas—illustrates the growing influence of state attorneys general on national policy, and their increasing willingness to deploy the resources of their offices to drive their policy preferences.

The phenomenon marks a new priority in for state attorneys general, emerging at a time when American politics has become more polarized.

“It used to be AGs would band together to fight big battles, but now there is a red and blue state divide.” said Neal Devins, a professor at William & Mary Law School in Williamsburg, Virginia, who tracks state attorneys general.

The historic shift, Devins said, comes as little surprise since partisanship in national politics has become more sharply defined.

“A red state is going to take the lead in checking the Democratic president.” he said.

And when Washington is gridlocked and unable to arrive at compromises in setting national policy, “there is a huge field available to the states,” Devins said.

Friends of the Court

The dispute between Exxon and Massachusetts began this spring when Healey's office sent an administrative subpoena to Exxon, requesting some 40 years' worth of corporate documents related to allegations that the oil company deceptively marketed and sold fossil-fuel products. Exxon responded with the suit in the Northern District of Texas asking for the preliminary injunction.

Texas Attorney General Ken Paxton led a 10-state coalition supporting Exxon, which includes AGs from Louisiana, South Carolina, Alabama, Michigan, Arizona, Wisconsin, Nebraska, Oklahoma, Utah and Nevada and filed a friend of the court brief.

On the other side are AGs from about 20 other states, including New York, Maryland, and Alaska, who also filed an amicus brief, but backing the Massachusetts AG.

In courts nationwide, state attorneys general are battling each other as they are in the Exxon litigation, not as only amicus filers, but often as plaintiffs in lawsuits against the federal government.

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Paxton has taken a leading role in the action. Since he entered office in January 2015, Texas has filed lawsuits against the federal government 15 times, and also continued to pursue the litigation that Paxton's predecessor initiated challenging policies of President Barack Obama. His office has also filed amici briefs in support of other plaintiffs suing the federal government.

His office has challenged the federal government's proposed reforms as they relate to: same-sex couple benefits, clean water regulation, Affordable Care Act fees, power plants' excess carbon emissions, federal land claims, refugee placements, air standards, oil-field methane regulations, disclosures of anti-union consultants and lawyers, transgender bathrooms, overtime pay, and most recently, the expiration of the federal government's contract with the Internet Corporation for Assigned Names and Numbers (“ICANN”).

A number of factors set the stage for Republican-led Texas to lead the charge challenging the Democratic-controlled White House's policies in court. Since plaintiff states challenging the federal government choose what court they file their case in, they find in Texas both one-judge courthouses where Republican appointees preside, and confidence that any appeals will land in the U.S. Fifth Circuit Court of Appeals, among the most conservative of the circuit courts.

Also Paxton certainly did not invent the idea of suing the federal government. Under the 12-year tenure of Paxton's predecessor, Greg Abbott, who is now Texas Governor, the Texas AG's office sued the federal government 31 times. But under Paxton, Texas' filing of cases against the federal government has accelerated. With less than two years of leadership, the Texas AG's office has filed already half as many cases challenging the federal government as Abbott did during his dozen years.

Paul Nolette, a political scientist who wrote the book Federalism on Trial: State Attorneys General and National Policymaking in Contemporary America, said in an essay on the “Library of Law and Liberty” blog that attorney general activism has become one of the most important developments in U.S. politics and governance.

“Once relatively obscure stepping-stone positions focused mainly on small-bore issues, state AGs make their presence known today in area after area, be it health care, environmental regulation, guns, immigration, or cultural issues,” said Nolette, who teaches at Marquette University.

One of the most important tools used by state attorneys general is to create broad coalitions. And attorneys general with different views may find themselves opposed by another grouping of states.

“The lawsuits they bring against federal agencies and the legal settlements they reach with corporations have led to stronger horizontal relationships among the AGs, and to any given AG's working with—or against—his or her counterparts in other states as part of multistate coalitions.”

In his essay, Nolette traced the phenomenon of attorney general activism to the time of the George W. Bush administration. But it has become even more salient during the Obama years, he wrote.

Challenging Executive Power

Bill McCollum, a former Florida Attorney General and partner in the Washington, D.C. office of Dentons, has first-hand experience in suing the federal government. As Florida attorney general he challenged the constitutionality of the Affordable Care Act.

“I believe you are seeing a very strong reaction to this administration's expansion of power as the number of state attorney generals, more than maybe it was historically, challenge the federal government,” McCollum said.

In a perfect world, the blue and red state divide would not set the chessboard, he said. “I really tried very hard to get some Democrats to do this. Some of them even told me, 'Bill, I think your arguments are perfectly right,” McCollum recalled. But ultimately, those Democratic AGs could not take the political risk of challenging a Democratic president, he said.

But Jeffrey Tsai, a partner in the Los Angeles and Silicon Valley offices of Alston & Bird, and former special assistant attorney general in California, downplayed how deeply the AGs in red and blue states are divided. “You see all of these lawsuits, where they are pitted against each other. At the same time, there are other investigations and prosecutions that are multi-state in nature and beyond any political lines. There Attorney General Offices are not as monolithic as they might seem. There are many careers lawyers working in these offices who are not identifying as Republicans or Democrats,” Tsai said.

At the Exxon hearing in September, however, Kinkeade seemed bothered about divisions among state attorneys general.

“I guess my concern is, is that you've got a group of very bright, well-meaning, thoughtful folks in the Northeast obviously disagreeing with, I think, bright, thoughtful, careful people in the Southeast and the Southwest,” the judge said.”… [I]t's just one of those things that are really sad…I'm just saying that is a very— it's problematic or it's not problematic. And I guess I don't—I mean, doesn't it concern y'all if we're kind of getting a us and them kind of a thing? I hate that.”

But then later Kinkeade asked Exxon's lawyer Anderson: “Why didn't you bring in the other states on your side?”

Anderson seemed confused.

“Bring them in?” he asked.

Kinkeade explained he meant add the supporting states such as Texas as parties rather than just amicus filers.

“You're telling me this is all political. If it is, I think I would bring in some political animals,” Kinkeade said.

Katelyn Polantz contributed to this story.