A federal judge brought the public one step closer on Thursday to discovering how much Exxon Mobil knew about its fossil fuel development's effects on the climate, as she threw out the company's lawsuit seeking to end a probe into its alleged cover-up.

The attorneys general of New York and Massachusetts are investigating whether the oil and gas giant lied to investors and the public about evidence of climate crisis in past decades. Exxon sued the two states after they subpoenaed documents showing its understanding of climate change and its communications with shareholders about the issue.

U.S. District Judge Valerie Caproni ruled against Exxon's argument that the two states are pursuing a "politically-motivated" attack on the company, and that its free speech rights were violated by the investigation.

New York Attorney General Eric Schneiderman applauded Caproni's decision, calling Exxon's case a "frivolous, nonsensical lawsuit that wrongfully attempted to thwart a serious state law enforcement investigation."

Maura Healey, Attorney General of Massachusetts, called the ruling "a victory for the people."

Environmental campaigners joined the attorneys general in celebrating the decision, and looked ahead to the likely outcome—evidence of what Caproni called Exxon's alleged attempts to "sow confusion" about climate crisis.