The Senate has blocked a bill that would have stripped senior military commanders of their authority to prosecute rapes and other serious offenses in the ranks.
The vote on Thursday was 55-45, short of the 60 necessary to move ahead on the legislation.
The Pentagon's leadership vigorously opposed the measure, arguing that officers should have more responsibility, not less, for the conduct of the men and women they lead.
Proponents of the bill sponsored by Sen. Kirsten Gillibrand insisted that far-reaching changes in the Uniform Code of Military Justice were necessary to curb the scourge of rapes and sexual assaults.
The showdown vote capped a nearly yearlong campaign by Gillibrand but was unlikely to be the final word.