The U.S. Virgin Islands attorney general has revoked his subpoena of the free market think tank Competitive Enterprise Institute as part of an investigation into ExxonMobil Corp. and the energy company’s research about climate change.

Claude E. Walker, the the Virgin Islands attorney general, is one of a 17-member network of state attorneys general who are investigating whether Exxon misled the public and investors about the harm of climate change.

But Walker went further than the other state attorneys general, by including subpoenas to private organizations like Competitive Enterprise Institute, seeking to obtain those groups’ communications with Exxon in order to find evidence that the energy company funded such groups to spread its message opposing climate change regulations.

After Competitive Enterprise Institute resisted Walker’s demands, and took to the public to express its displeasure, Walker has agreed to revoke the subpoena.

Still, the Competitive Enterprise Institute will continue to pursue sanctions against Walker in court because the nonprofit believes the attorney general violated its right to free speech.

“CEI is going forward with our motion for sanctions because Walker’s withdrawal only strengthens our claim that this subpoena was a constitutional outrage from the very beginning, violating our right to free speech and our donors’ right to confidentiality, and threatening the right of all Americans to express views that go against some party line,” said Sam Kazman, the general counsel for the Competitive Enterprise Institute, in a prepared statement.

The withdrawal of the subpoena comes after Republican attorneys general of Texas and Alabama filed motions to block Walker’s investigation.

It also comes after the Competitive Enterprise Institute took out a full-page advertisement in The New York Times last week opposing Walker’s action.

Linda Singer, an attorney representing Walker, sent a letter May 13 to a lawyer representing Competitive Enterprise Institute defending the subpoena as being issued legally under the Virgin Island’s “statutory authority in the course of a law enforcement investigation.”

Singer wrote that Walker did not violate Competitive Enterprise Institute’s right to free speech because the subpoena is part of an investigation into potential fraud, and “the First Amendment does not shield fraud.”

“This subpoena neither restricts CEI’s speech nor compels speech,” Singer wrote. “It simply seeks the production of documents related to an investigation that is not targeting CEI.”

While Walker ultimately agreed to remove the subpoena against Competitive Enterprise Institute, Singer, in her letter, left open the possibility that it could be reissued over the course of the investigation into Exxon.