The strongest legal test yet of whether a state can control nuclear power within its borders -- even shut down an operating atomic plant -- may emerge from Maine balloting on Sept. 23.
Voters will be asked at the polls to ban the generation of electricity by nuclear fission because it "presents an inherent and unreasonable risk of economic, physical, and mental harm."
The referendum's wording is important because, if passed, it likely will face a court challenge based on the 1954 Atomic Energy Act, which grants control of nuclear health and safety matters to the US government.
An exhaustive court fight is expected to be waged by the Central Maine Power Company if the anti-nuclear law is approved. The law would force shutdown of the firm's atomic plant in Wiscasset, the only nuclear generating plant in the state.
Pro-nuclear forces have raised $780,000 -- much of it from outside Maine -- for a media campaign to persuade voters to vote "no." The Maine Nuclear Referendum Committee and 22 other community anti-nuclear groups report arising $ 179,000.
Public discussion, including a series of statewide debate panels, has entered on the costs and consequences of alternative energy sources -- particularly coal and hydropower -- and the impact of conservation, if the plant is closed.
Although there is some doubt that, under federal law, the plant could be shut down, US Rep. David F. Emery, whose congressional district includes the embattled plant, says that if the referendum passes, "there will be tremendous political pressure that will eventually lead to its closing."
Except in Montan, where in 1978 voters said "no" to nuclear power before any atomic plants could be built, other state and anti-nuclear referendums have failed. And in California, New York, and Minnesota, federal courts have overruled state assumption of authority over nuclear power:
* A federal judge ruled that New York City could not regulate an atomic reactor at Columbia University.
* The Minnesota case went all the way to the US Supreme Court, which affirmed in 1972 that the state could not require stricter radiation emission controls over nuclear plants than the federal government.
* The California Energy Commission is appealing a US district court judge's ruling that three 1976 state laws on nuclear power -- including one that regulates nuclear construction and one that blocks new plants until a waste disposal method is devised -- violate fedearl authority.
Harvard Law Prof. Lawrence H. Tribe, who will represent California when that appeal is heard Oct. 9, says: "A Maine ban on the commercial sue of nuclear power would ultimately withstand federal constitutional challenge." The "supremacy" clause of the US Constitution, which says federal laws override contrary state laws, would only apply to the 1954 Atomic Energy Act in cases where the state regulates radiation exposure, he contends.
"The federal act provides a nuclear option to the states, not a nuclear mandate," he says. "The states can decide whether to have nuclear plants and the federal government decides how to operate them."