While her bill is designed to make victims more comfortable reporting crimes, some supporters contend that General Sinclair’s case may demonstrate another reason why it is needed: to ensure weaker charges are not pushed by senior officers who fear hurting their careers if they fail to act firmly.

That is a real concern, they say, given the unequivocal statement last year by President Obama that sexual offenders in the military should be “prosecuted, stripped of their positions, court-martialed, fired, dishonorably discharged.”

They also cite examples like that of Lt. Gen. Craig Franklin of the Air Force, who retired in January under pressure from lawmakers, including Senator Claire McCaskill, Democrat of Missouri, after his decision to overturn a sexual-assault verdict drew protests and spurred calls for overhaul.

In the Sinclair case, the chief prosecutor, Lt. Col. William Helixon, quit after telling another military lawyer he could not proceed with the case unless the most serious charges were dropped. That came after he raised concerns about the veracity of recent testimony by the general’s former lover — the only accuser on the most serious charges — which he felt would make those allegations very difficult to prove. (The new Army prosecutor concedes that the accuser’s testimony at a January hearing did seem to conflict with forensic evidence, but he said prosecutors do not question her story about being forced to perform oral sex.)

General Sinclair, 51, a former deputy commander of American forces in southern Afghanistan, is one of the highest-ranking officers to face court-martial in recent times. If convicted of the most serious charges, including forcible sodomy, he could face life in prison and sex offender registration. He also faces lesser charges based on other soldiers’ testimony, and has offered to plead guilty to conduct unbecoming an officer and adultery.

The general, who has served in the military for three decades, has admitted to a three-year consensual affair with his main accuser, a 34-year-old captain who had worked for him.

Richard L. Scheff, the general’s lead defense lawyer, supports Senator Gillibrand’s proposal, saying there is no way an independent military prosecutor would still be pursuing the most serious charges, given what he characterized as clear-cut perjury by the only prosecution witness for those allegations.