The chief of the Justice Department’s civil rights unit has asked a federal judge to sentence a Louisville police officer convicted in the 2020 killing of Breonna Taylor to one day in prison, a stunning reversal of the unit’s longstanding efforts to address racial disparities in policing.

Last year, a federal jury in Kentucky convicted Brett Hankison, the officer, of one count of violating Ms. Taylor’s civil rights by using excessive force in discharging several shots through Ms. Taylor’s window during a drug raid that went awry.

He faces a maximum sentence of life in prison, and a judge will consider the government’s request at a sentencing scheduled for next week.

On Wednesday, Harmeet K. Dhillon, the assistant attorney general for civil rights, asked the judge in the case, Rebecca Grady Jennings, to sentence Mr. Hankison to to one day in prison — essentially the brief time he had served when he was charged — and three years of supervised release.