Massachusetts Attorney General Maura Healey on Friday rebuked the oil industry's argument that its denial of climate change decades ago was protected speech under the First Amendment.

Healey has sued ExxonMobil for deceiving shareholders and consumers about the effect its products had on the environment by hiring scientists who denied climate change.

“I can assure you that whoever the CEO is doesn't begin to know the first thing about the First Amendment,” Healey said on Boston Public Radio. “For far too long these, these corporations have tried to use the First Amendment to shield unlawful activity, serious fraud and misrepresentation both to the investor and shareholder, public as well as to consumers, which is what we allege that ExxonMobil did. So we're gonna continue to fight on.”

Healy made the remarks during her monthly appearance on GBH’s Ask The AG. During the hourlong program, Healey touched on her efforts challenging Texas’ highly controversial ban on abortion, and the need to keep the political pressure on Facebook CEO Mark Zuckerberg and claims that it profited from the spread of misinformation.

But Healey returned repeatedly to her environmental concerns.

“I can't talk enough about climate change,” she said. “This is so imperative.”

She said she was relieved to see oil executives from the nation’s largest oil producers — ExxonMobil, BP, Chevron and Royal Dutch Shell — brought before the House Committee on Oversight and Reform Committee on Thursday. The group was grilled by Democratic legislators about claims that they cast doubt on how their products affected rising greenhouse gas levels and climate stability for decades.

ExxonMobil CEO Darren Woods said at the hearing that the corporation does not currently support climate denial. But ExxonMobil did countersue Healey’s office, alleging that her lawsuit unfairly punished ExxonMobil for exercising its First Amendment Rights.

Healey said her office’s research found that ExxonMobil paid scientists who became the climate deniers and served their corporate interest. And that the case has moved to the discovery phase.

“We're gonna continue to fight on and keep beating them,” she said.

When asked about Sen. Joe Manchin’s (R-West Virginia) efforts to remove key language from the President Joe Biden's climate agenda because of his personal interests in the coal industry, Healey called it disturbing.

“I lost regard for Joe Manchin because the position he's taking now just is really, really irresponsible and selfish,” she said. "That said there are ways forward and we've just got to just got to keep keep right at it.