Mill insisted that proponents of any idea must have full liberty to assert and discuss their belief, no matter how immoral their opinion may be considered. For example, even if it's considered immoral to compare climate scientists to the Unabomber, climate change debaters must have freedom to express that idea (The Heritage Foundation erected such a billboard).
But Mill attached one limit to free speech: "the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others." Regarding free speech, harm is typically limited to endangering the rights or lives of others.
Scientists and politicians who ask the Department of Justice to investigate Exxon's activities aren't curtailing free speech. Rather, DOJ is responsible for collecting evidence and determining whether or not Exxon and others knowingly spread misinformation about their products. Did they lie to derail open public discussion of climate change and delay government action? Has the public been harmed by these delays?
U.S. courts already ruled that Tobacco industry officials harmed people by testifying fraudulently, and knowingly promoting false assurances about their products. Our society doesn't protect the advertising of flagrant untruths about commercial products, nor the advertising of dangerous products like cigarettes to children. Only a DOJ investigation can determine if evidence exists to pursue a similar lawsuit against fossil fuel conspirators.
Jay Ambrose's byline should say that he's with the Independence Institute, which has ties to ALEC, State Policy Network, the Competitive Enterprise Institute, and therefore to those who erected that immoral billboard. Exxon and the Koch brothers fund some or all of these organizations.
Rabbi Judy Weiss