Gillibrand said nearly one-third of those who commit a sex crime in the military remain in military service because branches have different ways of handling the situation.
Sens. Susan Collins (R-Maine) and Olympia Snowe (R-Maine) co-sponsored the amendment.
Sen. Patty Murray (D-Wash.) introduced Amendment 3099, which she said improves the mental health and suicide services provided by the Department of Defense.
Murray said the bill sets up a suicide prevention program across the department, provides peer counseling and extends mental health services to the family of service members.
The Senate continues to consider amendments to the National Defense Authorization Act, S. 3254, Wednesday.
—This article was updated at 3:40 p.m.