[JURIST] Wisconsin Gov. Jim Doyle [official website] has announced that the state will join nine others in suing the Environmental Protection Agency [official website] over a recently announced rule [JURIST report] to reduce mercury emissions. The lawsuit, led by New Jersey Attorney General Peter Harvey [official website], alleges that the rule violates the Clean Air Act because it does not regulate mercury as a hazardous air pollutant. Under the new mercury rule, a cap-and-trade program is used to reduce emissions, rather than the technology-based standard normally required for listed hazardous air pollutants. Harvey contends that the technology-based rule would reduce emissions by 90 percent, more than the 70 percent reduction expected under the Clean Air Mercury Rule [EPA backgrounder]. It would also avoid "hot spots" by requiring equal reductions by every mercury emitter. Proponents of the EPA rule argue that the trading route is more efficient and less costly for businesses to implement. The other states participating in the suit are California, Connecticut, Maine, Massachusetts, New Hampshire, New Mexico, New York and Vermont. Read a press release from Doyle's office. AP has more.