Rule 23(a) requires a defendant to waive her right to a jury trial in writing. On February 5, 2018, the Ninth Circuit in United States v. Laney, No. 15-10563, joined other circuits in holding that a presumption of validity does not attach to a jury trial waiver signed only by defense counsel. The court, however, explained that the absence of the defendant's signature will not constitute reversible error if the record otherwise shows that the defendant's waiver was voluntary, knowing, and intelligent. In making that assessment, the court stated that jury trial waivers are evaluated in the context of the time of the waiver, not in retrospect after the trial is complete. In Laney, the record did not otherwise show a voluntary, knowing, and intelligent waiver at the time of the waiver, and thus, the court found structural error, reversing and remanding the case to the district court.
The decision of the Ninth Circuit is here.