In April, the email in-boxes of energy executives filled with alerts from the nation's top corporate law firms. The subject: the multistate investigation into whether Exxon Mobil committed fraud by publicly discounting the impact of fossil fuels on climate change. The investigations into whether their industry suppressed findings and misled investors, policymakers and the public about global warming not only raise the prospects of criminal charges, but add momentum to a legal campaign [comparable] to the decades-long battle against Big Tobacco. In April, a federal judge in Oregon ruled that a case against the U.S. government for inaction on climate change could proceed, explaining that the alleged valuing of short term economic interest despite the cost to human life" required examination by the courts. Environmental lawyers have argued for years that governments and companies are legally obligated to reduce greenhouse gas emissions. They had little success, with the U.S. Supreme Court ruling in 2011 that the federal government alone had the power to control carbon emissions. But the recent entry of state prosecutors into the legal battle opens up a new line of inquiry: Did fossil fuel companies mislead their investors and the public on their own views on climate change and the risk it posed to their business? The recent legal rush follows the revelation last year that Exxon had engaged in climate change research in the 1970s and '80s, and was warned by its own scientists of the growing threat.