UPDATE (December 12, 2016 at 5:05 am ET): The group 350.org, as well as the Rockefeller Brothers Fund, the Rockefeller Family Fund and Michael Northrop, the sustainable development program director of RBF, have filed motions to quash subpoenas issued against them by Exxon. The motions were filed in a New York federal court and argue Exxon's subpoenas should be invalidated because the material being sought is protected by the First Amendment. Northrop is on the board of directors of ICN, and RBF and RFF are among 18 major funders of ICN.

In its continuing offensive to beat back investigations of possible climate fraud, ExxonMobil is now engaged in a fight with several environmental advocacy groups as it demands to see their records.

Exxon, in carrying out discovery in litigation about probes of its record, hit at least seven non-governmental organizations and individuals with subpoenas last month.

The subpoenas demanded documents and communications that could reveal behind-the-scenes involvement the organizations had with state attorneys general investigating or contemplating investigations of Exxon.

Now, several of those targeted by Exxon's subpoenas have come out fighting, flatly refusing to comply and denouncing Exxon's strategy. Many of them are also resisting subpoenas by an important Exxon ally, Rep. Lamar Smith, the chairman of the House Science Committee. But Exxon's actions are especially remarkable as an example of a giant corporation going after advocacy organizations for their activities.

"In our view, with its subpoena, Exxon Mobil attempts to abuse third-party discovery in its lawsuit in the Northern District of Texas by using it as a weapon against climate change activist groups like 350.org," according to a letter to Exxon lawyers from 350.org attorney Abbe David Lowell. It referred to a federal court where Exxon is fighting the state attorneys general.

"Rather than seeking real discovery and information relevant to jurisdiction in the Lawsuit, the subpoena and other efforts to broadly investigate 350.org's advocacy appear to he attempts to chill 350.org's exercise of its First Amendment rights, including the rights to free speech, to free assembly and to petition government," said the letter, written by Lowell, a leading free-speech lawyer.

An Exxon spokesman did not respond to a request for comment.

Exxon's assault on the advocacy groups and individuals can be traced to an October discovery order against Massachusetts Attorney General Maura Healey.

The order, issued by a Texas federal court judge overseeing Exxon's lawsuit to block Healey's investigation of the company, was initially interpreted as opening the door for an in-depth review by Exxon of her office's internal communications and other records related to the investigation.

But, emboldened by that order, Exxon launched an offensive. It went on record as saying every one of the 17 attorneys general who teamed up in March to form the AGs for Clean Power coalition could become targets of subpoenas.

The company set its sights on the environmental groups in October, sending a letter cautioning them to preserve documents and correspondence related to their interactions with the attorneys general. Exxon also told them to hold on to their communications with members of the press.

In addition to raising a constitutional objection, 350.org's lawyer cited 13 other general objections to the subpoena, which he said goes beyond seeking documents that could be relevant to Exxon's lawsuit against Healey.

The Exxon subpoena to 350.org lays out a dozen areas the company wants to explore through a comprehensive review of the organization's internal records.

"This request includes any communications in which 350.org advocated that an Attorney General initiate an investigation of ExxonMobil, participate in the Green 20 Press Conference, announce approval for or alignment with the investigation of ExxonMobil by any Attorney General, and/or collaborate, cooperate, or work in concert with Attorneys General who were or are investigating ExxonMobil," according to the subpoena. The press conference was March 30 and featured former Vice President Al Gore who praised the attorneys general.

The subpoena also sought records in a number of other areas including:

Communications pertaining to decisions of an attorney general regarding whether to investigate Exxon.

Communications in which 350.org advocated that an attorney general initiate an investigation of Exxon.

Fees or expenses paid to Gore in connection with his participation in or attendance at the news conference announcing the attorneys general coalition.

Documents, recordings, or materials presented during a 2012 conference focused on holding the fossil fuel industry responsible for climate change.

Records concerning the actual or anticipated participation of Exxon or other fossil fuel companies or trade associations in the international climate negotiations in Paris last December.

Documents and communications concerning fundraising for candidates for political office, including fundraising for any member of the attorneys general coalition.

"We must be doing something right to get subpoenaed by the world's largest oil company. Clearly the revelations about Exxon's climate cover-up have hit a nerve," said Jamie Henn, 350.org communications director.

"Rather than admitting the truth, Exxon is trying to distract the public by directly attacking us. Instead they're just proving our point: when faced with an opportunity to come clean, Exxon is falling back on its long history of deceit, denial and delay."

The Union of Concerned Scientists is another organization resisting an Exxon subpoena. Jay Ward Brown, an attorney for the organization and for its director of science and policy, Peter Frumhoff, said all of the information Exxon wants is publicly available on the organization's website, yet he raised a series of objections that signal the organization will not be bullied.

"Dr. Frumhoff objects to the Requests on the ground that ExxonMobil is not entitled to have its cake and eat it, too," according to a letter from Brown to Exxon.

"In the underlying litigation, ExxonMobil alleges that the requests by the Attorneys General for the company's own climate change-related documents are part of an 'apparent effort to silence, intimidate, and deter those possessing a particular viewpoint' from participating in the 'debate' over climate change.

"It appears that such intimidation is precisely ExxonMobil's intent in issuing the subpoena to Dr. Frumhoff."