Fayetteville, Pa.

Raymond Cromartie grew up an Army brat. He looked up to his father, James, who retired in 2003 as a lieutenant colonel in the Medical Service Corps. "There's been so many people in the past—men and women that have died in the service of our country—that I don't think I should be sitting on my butt while they sacrifice their lives," the 23-year-old Mr. Cromartie tells me in an interview at his parents' home some 20 miles west of Gettysburg.

Trent—he goes by his middle name—received an appointment to the U.S. Military Academy at West Point, N.Y., and entered in 2010. A year later, a female cadet charged him with sex crimes. Today his aspiration to serve is in jeopardy even though a court-martial acquitted him. His story illustrates both the human toll and the cost to the country of the current moral panic over sexual assault in the military.

Mr. Cromartie learned he was a suspect late in the afternoon on July 20, 2011—the day after he finished his field training exercise, a grueling three-day combat simulation in 90-degree summer heat. His company commander told him to report immediately to the campus military police station. Weakened and hungry—he was still recovering from the exertion and sleep deprivation, and he hadn't eaten dinner—he was subjected to a 6½-hour interrogation.

The investigator, Special Agent Craig Butler, began by telling him he stood accused of multiple serious crimes, including sexual assault and forcible sodomy, but withheld details of the allegations. "I was extremely confused," Mr. Cromartie recalls. "My mind started going a mile a minute. I was trying to figure out where it could have even come from." Amid his discomposure, he signed a waiver of his right to counsel.

The alleged attack turned out to have occurred during an academy-sponsored ski trip to Mont-Tremblant, Quebec, in January 2011. The 180 cadets on the trip had been told they were permitted to drink, but only if they were over 21 (Quebec's drinking age is 18) and only in public places like bars and restaurants. Both those limits were widely flouted.

The accuser would later describe the trip as "a bad parody of 'American Pie,' " the raunchy 1999 high-school comedy. "People were hanging out balconies and hanging around drunk all the time," she testified. "People were also kissing and having sex in almost every room."

Mr. Cromartie calls that an overstatement—"I wouldn't say it was a huge sex-fest"—but he agrees there was scant supervision and widespread drinking at the hotel, including by him. He also acknowledges a sexual "hookup" with the accuser, which occurred in the hotel bedroom she shared with three other female cadets. But while her account and his agree on some of the physical details, he denies her claim that he forced himself on her.

Although the accuser waited half a year to file charges, on the night of the incident she did phone Second Lt. Scott Wright, a young Army officer she described as a family friend. After hearing her version of events, Lt. Wright assumed the role of white knight. He demanded that she file a formal complaint. She demurred, so the next day, over her objection, he alerted the academy. "What that bastard did to you is vile and unforgivable," he texted her. "You can't let this go. I did what I had to do; what I knew in my heart to be right."

The officer in charge of the trip, Maj. Jonathan Bodenhamer, summoned the accuser to his hotel room. "I brought her in thinking she had been raped," he testified. What she told him sounded more like regret than rape: "I was very careful to look out for those words and triggers and descriptions of events that would lead me to believe that an assault was being reported. She didn't say he forced her, that she said 'no' or 'stop,' or that she couldn't get away." He concluded it was a false alarm.

The investigation wrapped up in April 2012, 15 months after the trip. The investigating officer, Lt. Col. Mark Visger, sent a memo to Brig. Gen. Theodore Martin, then commandant of cadets. "I feel that it is my duty to inform you that a trial will be difficult and there are significant challenges to proof beyond a reasonable doubt," Col. Visger wrote. But he had it both ways, also finding "reasonable grounds to support the charges and proceed to general court-martial." After multiple delays, the trial began in October 2012.

If anything, Col. Visger understated the threadbareness of the prosecution case. Since there were no eyewitnesses to the sexual activity, it was she-said/he-said. Because the accuser failed to report the incident immediately, there was no physical evidence.

And the accuser's testimony diverged from that of other witnesses. Most notably, she testified that she was a virgin at the time and that the alleged attack caused her to bleed profusely. "There were four or five streaks . . . 24 inches wide, 6 inches deep blood streaks along the side of [the] bed, which had white sheets," she testified. Her roommates "were grossed out by it and wondered whose blood it was," the accuser added. "I volunteered to sleep on that bed the next night." All three roommates testified that they never saw any blood and that no such discussion of sleeping arrangements occurred.

Mr. Cromartie was acquitted of all the accuser's charges. A few days later, he sent a brief no-hard-feelings email to now First Lt. Wright, who responded with a long, effusive apology. Lt. Wright wrote that after learning the facts of the case, "I was shocked and appalled. I felt as though I had been used and manipulated." When he heard of the acquittal, "I thanked God that I didn't play a part in sending an innocent man to prison."

But Mr. Cromartie's ordeal was not over. He had fallen into a perjury trap—ironically, as a consequence of his conscientiousness.

Agent Butler testified that when he interviewed Mr. Cromartie, he had already taken the accuser's statement and "preloaded some of the questions" for the accused. One point on which the accounts differed was the pair's location when he touched her genitals. He said it happened only in her bedroom; she cited multiple places in both of their suites, which were adjacent. As Mr. Cromartie explains it to me, he became confused by questions about his touching her while they were in particular spots and at one point answered: "I didn't finger her." That flat denial made it into his signed attestation, which was typed by Agent Butler and is the only record of the interrogation.

Two days after that interview, Mr. Cromartie returned and told a different agent he wanted to amend his statement. This time he acknowledged the act he'd ended up denying earlier. The court-martial panel found him guilty of making a false official statement—a statement that was provably untrue only because Mr. Cromartie had taken the trouble to set the record straight.

The panel could have sentenced him to separation from the academy, analogous to expulsion from a civilian college. Instead it chose a milder punishment: a reprimand and 30 days' restriction to quarters, the Army equivalent of house arrest. But late last month he was separated anyway, through an administrative action recommended by the West Point superintendent, Lt. Gen. David Huntoon.

Mr. Cromartie's civilian lawyer, Bill Cassara, has appealed the conviction to the Army Judge Advocate General's office. He tells me he's confident that West Point will readmit his client if the appeal succeeds. It argues that Mr. Cromartie's decision to amend his statement demonstrates that he had no intent to deceive, one of four elements that must be proven to convict a serviceman of a false official statement.

The appeal also alleges that the conviction is tainted by both political pressure and favoritism toward the accuser, or the appearance thereof. The legal term is unlawful command influence, or UCI.

The politics of sexual assault weigh heavily on West Point owing to a lawsuit by a former cadet who alleges an upperclassman raped her. In April 2012, then-Defense Secretary Leon Panetta said on CNN: "We've got to train commanders to understand that when these complaints are brought, they've got to do their damnedest to see that these people are brought to justice." Less than a month passed before Gen. Huntoon referred Mr. Cromartie's case for a general court-martial. (More recently, a similar statement by President Obama has raised militarywide concerns about UCI. Prejudicial comments by members of Congress are no less irresponsible but do not constitute UCI, as lawmakers are not in the chain of command.)

In addition, in October 2011 the accuser's father sent an inflammatory three-page handwritten letter to the commandant, Gen. Martin. The father asserted that his daughter had been "raped" and repeatedly referred to Mr. Cromartie as a "rapist." (This was not in fact a rape case; even the accuser said the sexual activity stopped well short of intercourse.) The letter began "Dear Ted." The father and Gen. Martin were classmates at the academy 30 years ago, and West Point classes are famously tightknit.

Perhaps the clearest indication of UCI came in April 2012, when the defense counsel asked Maj. Jeffrey Pickler, Mr. Cromartie's company tactical officer, to write a letter attesting to the cadet's good character. Maj. Pickler agreed, then sought advice from his superior, Lt. Col. John Vermeesch, who discouraged him from writing the letter. Maj. Pickler testified that Col. Vermeesch prefaced his recommendation with a pre-emptive denial: "Just to be clear, this is not UCI."

Although Maj. Pickler didn't write the letter, he testified as a defense witness and spoke glowingly of Mr. Cromartie: "He strikes me as the kind of cadet who has worked incredibly hard to get here, he is extremely mature compared to his peers and classmates, he is hard working, and [he] possesses incredible work ethic." That's what the Army is losing if it allows his separation to stand.

After the court-martial panel read its verdict, Mr. Cromartie took the stand in the proceeding's sentencing phase to show remorse for the misstatement: "I should have reviewed my statement thoroughly. I just skimmed it and it was my fault," he testified. "I should have asked for a lawyer."

If that is the most important lesson a young man can learn at West Point, it is an indictment of both the academy's leadership and the country's.

Mr. Taranto, a member of the Journal's editorial board, writes the Best of the Web Today column for WSJ.com.