Federal prosecutors are asking a judge to block environmental activist Tim DeChristopher from claiming his civil disobedience during a federal oil and gas auction was "necessary."

"Necessity can never be a defense to the type of protest-driven offenses that the defendant has committed," assistant U.S. Attorney John Huber wrote in a motion filed Friday in U.S. District Court in Salt Lake City.

The U.S. Attorney's Office for Utah acknowledged in its court filing that it was DeChristopher's attorney who first told them he planned to use a "necessity" or "choice of evils" defense, referring to a legal concept where a defendant claims his conduct was necessary to prevent a greater evil from taking place. In DeChristopher's case, he is accused of sabotaging last year's Bureau of Land Management auction of oil and gas leases in some of Utah's most pristine and spectacular wilderness.

The auction drew protests and lawsuits, and DeChristopher has been championed as an eco-hero for his actions in making false bids and driving up the prices on others. He has pleaded not guilty to a single charge of violating the federal Onshore Oil and Gas Leasing Reform Act and making a false statement. He will go on trial in July.

The U.S. Attorney's Office insists he broke the law and seeks to limit his defense to a black-or-white answer.

"After he committed the charged offenses, and since a grand jury issued an indictment against him, the defendant has found his voice," Huber wrote. "From forum to forum, he has publicly espoused the evils of the BLM oil and gas leases that he tried to sabotage through evil acts. On the other hand, he has championed his personal choice to commit purported lesser evils — criminal acts — in the name of climate justice. In the end, though, his views merely represent one segment of the population."

DeChristopher's attorney, former BLM director Pat Shea, said he wants to make global warming a key issue at trial.

"They'd be happy if the trial went on for two hours and the jury came back guilty," he told the Deseret News on Friday. "We've said it's going to take five days, and it's going to be an effort to, one, prove in a judicial setting the nature of global warming, and the necessity for direct action which Tim's activities on Dec. 19 represented."

E-MAIL: bwinslow@desnews.com