In his latest showing of support for Big Oil, a House Republican has subpoenaed state attorneys general and environmental groups that are investigating whether companies like Exxon Mobil committed fraud by covering up the risks of climate change.

Rep. Lamar Smith (R-Texas) said during a press conference Wednesday that the subpoenas are necessary to protect the American people from further infringement of their free speech rights.

Smith, who chairs the House Committee on Science, Space, and Technology, has a long history of denying climate change and going after those who accept the scientific consensus.

The investigations led by the attorneys general of New York and Massachusetts , Smith said, amount to a form of extortion, threaten legitimate scientific debate about climate change and are a blatant effort to silence free speech.

The congressmans First Amendment argument is also a go-to defense for the oil industry in its fight to keep buried what it knew about the effects of fossil fuels and when.