The decision was a victory for Monsanto and others in the agricultural biotechnology industry, and it could have an impact on other cases, such as one involving genetically engineered sugar beets.

"Monsanto and farmers in the United States are thrilled with this decision, which is far-reaching in its look at the regulatory framework that should govern biotech crops," David F. Snively, Monsanto’s general counsel, told reporters in a conference call.

But in practice it is not clear whether the decision will measurably speed up the resumption of planting of the genetically engineered alfalfa.

A federal district judge in San Francisco ruled in 2007 that the Agriculture Department had approved the genetically engineered alfalfa for commercial planting without adequately considering the possible environment impact, as required by federal law. The judge vacated the approval of the crop and also imposed a nationwide ban on planting those seeds, decisions later upheld on appeal.

But the Supreme Court, in a 7-to-1 decision, said the lower court judge had gone too far in imposing the nationwide ban because it prevented the Agriculture Department from considering a partial approval, known as deregulation, which would have allowed some of the alfalfa to be grown subject to various conditions.

"The district court barred the agency from pursuing any deregulation — no matter how limited the geographic area in which planting of RRA would be allowed," Justice Samuel Alito wrote in the opinion, referring to Roundup Ready alfalfa.

Justice John Paul Stevens was the lone dissenter. Justice Stephen Breyer did not take part in the case because his brother, District Judge Charles Breyer, had handled the case in the district court.

But the Supreme Court’s decision still leaves in place the lower court’s ruling that vacated the approval of the crop. So the Agriculture Department must either fully or partially approve the crop before growing can resume.

"I think the practical impact is nil," said George Kimbrell of the Center for Food Safety, a Washington advocacy group that was part of a coalition of environmental groups and organic and conventional alfalfa farmers who had challenged the crop’s approval. Mr. Kimbrell said the Supreme Court had “set aside the suspenders and left the belt in place."

The Agriculture Department finished a draft of an environmental impact statement in December, concluding that there would be no significant harm from approving the alfalfa. But the department must now consider more than 200,000 public comments it received before completing the statement. It has said it anticipated finishing next April.

But the Supreme Court’s ruling could affect a similar case, also brought by the Center for Food Safety, involving Roundup Ready sugar beets.

In that case, a different federal judge in San Francisco ruled last September that the Agriculture Department had failed to adequately assess the environmental impact of its approval of the biotech crop.

Planting has continued, however, because the judge, Jeffrey S. White, has not yet ruled on a remedy. The Supreme Court’s decision makes it highly unlikely that he will issue a blanket ban on the growing of the genetically engineered beets.

Roundup Ready alfalfa and sugar beets were the newest additions to Monsanto’s extremely successful lines of Roundup Ready soybeans, corns and cotton. The alfalfa had not been that widely planted before it was banned. But the Roundup Ready beets have caught on quickly and now account for the vast majority of beets planted in this country.

The crops contain a bacterial gene that allows them to withstand spraying with Roundup or its generic equivalents, known as glyphosate. That allows farmers to spray their fields to kill weeds while leaving the crop intact, making weed control easy.

The environmental groups and others had said that the foreign gene might spread to organic or conventional nongenetically engineered crops, hurting sales of organic farmers or exports to countries like Japan that did not want genetically engineered varieties. They also said the widespread use of Roundup would lead to development of weeds resistant to the herbicide.

Judge Breyer agreed with this in the lower court. Monsanto appealed, joined by some alfalfa growers who wanted to plant the Roundup Ready crop, and by Forage Genetics International, an alfalfa breeder that was handling the sale of the Roundup Ready seeds.

(Published by The New York Times – June 21, 2010)