Forcing United States attorneys to seek the death penalty could result in unwanted ripple effects, such as more frequent acquittals... There is also a risk that jurors who believe that a defendant does not warrant capital punishment could vote to acquit him on capital charges, or that judges who think the government has overreached could try to undermine prosecutors' cases, several former prosecutors said.

"The judge can take it out on you with all sorts of discretionary rulings," said Jamie Orenstein, a federal prosecutor in Brooklyn in the 1990's and a member in 2000 of the committee that reviewed death penalty cases for Attorney General Janet Reno.

"It's the exhibit that the judge doesn't admit," Mr. Orenstein said. "It's the objection to the prosecution's testimony that the judge sustains. It's the juror with qualms about the death penalty who the judge allows onto the jury."