Lawyers say decision to bomb should not determine whether suspect should receive death penalty.

Lawyers for accused Boston Marathon bombing suspect Dzhokhar Tsarnaev asked a federal judge Wednesday to prevent prosecutors from arguing for the death penalty simply because a crowded athletic event was targeted.

They also want Judge George O’Toole to declare the death penalty unconstitutional, in part because of the recent botched executions in Oklahoma and Ohio.

Tsarnaev’s lawyers argued that because prosecutors already claim the 2013 attack was an act of terrorism that followed extensive planning, the jury should not consider the death penalty just because the race was the target.

“Stated differently, the allegation that Tsarnaev targeted the marathon is simply a more specific statement of the substantial planning allegation,” the lawyers wrote in a court filing. Therefore, jurors should not consider it an “aggravating factor” in any sentencing deliberations.

Last week, the defense moved to strike another aggravating factor cited by the U.S. attorney — the alleged betrayal of the United States by the naturalized citizen. They said having duplicative aggravating factors “can have no other effect than to introduce arbitrariness and unfairness into the jury’s sentencing deliberations.”