"There will be a strict timetable for judicial proceedings that will allow the imposition of the death sentence without undue delay," Barr said of the legislation during remarks to law enforcement in New Orleans. "Punishment must be swift."
Barr said he expects the proposed legislation to be ready by the end of the Labor Day holiday.
"Today, I’m also directing the Department of Justice to propose legislation ensuring that those who commit hate crimes and mass murders face the death penalty, and that this capital punishment be delivered quickly, decisively, and without years of needless delay," Trump said a week ago.
Opponents of the death penalty, however, have noted that there's little evidence to suggest that quicker executions would amount to a deterrent in the cases of mass shooters -- who often mount their attacks with plans to take their own life or to be killed by law enforcement at the scene.
The El Paso shooter, for instance, carried out his attack in Texas, where far more prisoners have been put to death by execution than any other state.
The announcement from Barr follows his move last month ordering the Bureau of Prisons to resume federal executions, beginning in December, which is expected to face significant legal hurdles.
Trump has long advocated for expanding use of the death penalty in the U.S. against cop killers and drug traffickers, even as several states have moved in recent years to ban or place a moratorium on executions. A majority of states, however, still allow for the death penalty.