Just how much power does a congressional committee have to issue broad subpoenas of state attorneys general and environmental groups?

That’s the issue the House Committee on Science, Space and Technology wrestled with Wednesday with members from both parties wrapping themselves in the First Amendment. Each side said the other was engaging in a kind of Red Scare, except instead of trying to squelch views on communism, they were attempting to silence views on climate change.

The background: In March, a group of the state attorneys general issued subpoenas for an inquiry into whether ExxonMobil concealed knowledge it had about climate change and misled the public and investors about its true views. The company says it has submitted about a million documents so far.

In response, Rep. Lamar Smith (R-Tex.), as chairman of the House Science Committee, issued subpoenas in mid-July to the New York and Massachusetts attorneys general and nine environmental and nonprofit organizations, seeking emails, phone records and other documents about conversations they had before the investigation of ExxonMobil, including conversations among environmental groups.

Republicans said the committee subpoenas were needed to prevent a chilling effect that the investigations by state attorneys general were having on ExxonMobil and on how they might deter Exxon from pursuing its own scientific inquiries.

Democrats said the committee’s subpoenas threatened the environmental groups’ free speech, freedom of assembly and freedom to petition government, and the ability of the state attorneys general to determine whether ExxonMobil committed fraud by publicly saying one thing about climate change while internally saying another.

At a hearing Wednesday, Smith defended the subpoenas he issued, saying the committee had “a constitutional obligation to conduct oversight any time” it believed scientific inquiry was “endangered.”

The ranking Democrat, Rep. Eddie Bernice Johnson (Texas), replied that “the law is clear: Fraud is not protected by the First Amendment. If any companies defrauded the public in their disinformation campaign on global warming, that is a matter for the state attorneys general, not the committee on science.”

The witness panel included Jonathan Turley, a George Washington University law professor who said that he agreed with the environmental groups on climate change but that the committee had every right to pursue its inquiry into the groups’ relationships with the state attorneys general through subpoenas.

It also included Elizabeth Price Foley, a law professor at Florida International University who said that federalism did not preclude the federal government from enforcing subpoenas and carrying out oversight, including into matters of scientific research.

Ronald D. Rotunda, a law professor at Chapman University who has been involved in litigation in Utah to transfer federal lands back to the states, testified that if congressional subpoenas could not be enforced then the Senate Watergate committee “would never have gotten off the ground.”

Rotunda said, “We want to know whether there was a corrupt agreement between the attorneys general, environmental groups and George Soros,” the billionaire investor who has supported a variety of liberal causes. He said the “committee has a right to know whether [New York Attorney General Eric] Schneiderman is working on his own or is part of a corrupt deal” to work with environmental groups.

He later said that the environmental groups would be proved wrong about climate change just as various studies, he said, had wrongly raised concerns about drinking coffee or eating red meat, eggs or whole milk.

Only Charles Tiefer, a law professor at the University of Baltimore and former acting general counsel to the House, said the committee’s subpoenas exceeded its authority.

He testified that Congress has never in more than 200 years issued a subpoena to a state attorney general. Tiefer said that “fraud investigation is the legitimate bread and butter of state attorneys general” and that if ExxonMobil did, in fact, say one thing about climate change internally and another publicly, that was something that could be investigated.

As for discussions between environmental groups and the state attorneys general, Tiefer said any contacts the groups had fell well within their rights to association and for the environmental groups to urge government to take action.

On Tuesday, a different group of law professors sent a letter to Smith defending the Union of Concerned Scientists, one of the groups subpoenaed. While Rotunda spoke of a “corrupt agreement,” the lawyers defending UCS said the group had conducted its activities publicly. They said the subpoenas placed an “onerous burden” on groups exercising their First Amendment rights to free speech and to petition government.

“You have to go back to the Red Scare to find something similar,” said Johnson, referring to congressional hearings in the 1950s into whether communists had infiltrated the U.S. government, Hollywood movie business and other parts of society.

“There is obviously a political agenda here, I believe,” said Rep. Paul Tonko (D-N.Y.). “These types of scare tactics threaten the vital work of many organizations.”

Rep. Dana Rohrabacher (R-Calif.) bemoaned a “breakdown in tolerance for people with different opinions” and backed Smith’s subpoenas. (The subpoenas were issued by Smith without a vote of the full committee.)

But Tiefer said the issue was whether Exxon committed fraud, adding that “Exxon Mobil can take care of itself.”

Clarification: This story left unclear the position of Ronald D. Rotunda, a law professor at Chapman University, on the issue of climate change. In testimony before the House Committee on Science, Space and Technology, Rotunda said: “Now, I assume that global warming is real and humans cause it.” He cautioned, however, that “the government has repeatedly been wrong about what is scientific truth” and listed studies of the effects of various foods.