In a Monday letter to Rep. Lamar Smith (R-TX), climate change denier and chair of the House Science Committee, several constitutional experts argued that the committee should not have issued subpoenas to environmental groups as part of its probe into state investigations of Exxon.

The scholars wrote in the letter obtained by InsideClimate News that “these Subpoenas violate the separation of powers, exceed the committee’s delegated authority, abridge the First Amendment, and undermine fundamental principles of federalism.”

“The Subpoenas should not have been issued and should not be enforced. We urge you to withdraw voluntarily these misguided demands for information your committee has no legitimate right to inspect,” the letter reads.

For a few months, the House Science Committee, has been looking into state investigations into whether Exxon Mobil misled its investors regarding climate change. The committee requested that several environmental groups and state attorneys general turn over their communications related to the Exxon probe and climate change. After the groups and state officials refused to turn over documents, the committee issued subpoenas.

The activist groups and state attorneys general have still refused to comply, prompting the House Science Committee to schedule a hearing for Wednesday seeking to affirm Congress’ right to issue subpoenas.

This is just the latest battle the Science Committee has waged over climate change. Last year, the committee issued subpoenas to the National Oceanic and Atmospheric Administration (NOAA), demanding internal communications of scientists that conducted research on climate change.

The Monday letter from the constitutional experts does not address whether the committee can issue subpoenas to state officials, but to the outside groups in this case. In the letter, the scholars argue that the investigation into communication that the environmental groups had with states falls outside of the committee’s purview, and that it violates individuals’ right to petition state governments.

The experts told the committee that the subpoenas are “invalid and constitutionally impermissible.”

“We urge you to withdraw them promptly. Should Congress seek to enforce them, we are confident that a federal court will take seriously the lessons this country learned from McCarthyism and refuse to do so,” the letter reads.