Nevada Secretary of State Ross Miller (D) filed a civil lawsuit this weekend against the Koch group Americans for Prosperity. The suit alleges AFP violated state law by not filing required registration and donor reports when it waded into a state Senate election this summer. AFP was behind several mailers targeting Nevada Senate candidate Kelvin Atkinson (D) over his support for renewable energy. The group also ran tens of millions of dollars in ads nationally, although AFP calls itself “an organization of grassroots leaders” that has avoided “express advocacy,” by not using words like vote or oppose in its ads. Miller seeks civil penalties and a court order for the organization to file contribution and expense reports for its ads against Atkinson.