THERE AREN’T all that many places in the world where law enforcement officers would move against a powerful millionaire based on the word of a poor, immigrant chambermaid. In fewer places still would the people who cuffed the suspect admit mistakes and later ask that charges be dropped.

Such is the imperfect beauty of the American justice system, as displayed in the case of Dominique Strauss-Kahn. Some critics, especially in France, have complained that Mr. Strauss-Kahn was unforgivably dragged through the mud. Others, by contrast, complain that the dropping of charges sends a chilling signal to rape victims generally. We don’t buy either complaint.

Then the head of the International Monetary Fund, Mr. Strauss-Kahn was arrested in May after Nafissatou Diallo, a maid at the luxury Manhattan hotel where he was staying, alleged that he sexually assaulted her. Investigators found Mr. Strauss-Kahn’s DNA on Ms. Diallo’s uniform and in spots in the suite where she said she had been assaulted. Supervisors who encountered Ms. Diallo shortly after the alleged assault told police of the victim’s distress and described her as a hardworking and loyal employee. Any responsible law enforcement official would have detained Mr. Strauss-Kahn before he could leave the country.

Once a leading contender for the French presidency, Mr. Strauss-Kahn was essentially forced to resign from his IMF post. His political prospects in France vanished.

Then Ms. Diallo’s story began to unravel. Over a period of weeks, prosecutors say, she contradicted key details of her original story, ultimately providing investigators with at least three versions, each less believable than the last. She admitted to fabricating a story about being gang-raped in her native Guinea; evidence emerged that she had lied about her income to obtain low-income housing. Prosecutors also learned that she had had a telephone conversation with her incarcerated fiance in which the topic of seeking money from Mr. Strauss-Kahn arose; she ultimately filed a civil suit against Mr. Strauss-Kahn seeking unspecified damages.

Ms. Diallo’s lawyer passionately defends the veracity of his client’s account and blames any inconsistencies on translation errors. But on Monday, Manhattan District Attorney Cyrus Vance Jr. recommended that the charges be dropped. “The nature and number of [Ms. Diallo’s] falsehoods leave us unable to credit her version of events beyond a reasonable doubt, whatever the truth may be about the encounter,” the district attorney’s office wrote. “If we do not believe her beyond a reasonable doubt, we cannot ask a jury to do so.”

It was the right call. Ms. Diallo’s lies about the previous rape and on the housing matter would have hurt her credibility, but they would not have been dispositive. The inconsistencies surrounding the alleged assault, on the other hand, doomed the case.

After his arrest, other episodes from Mr. Strauss-Kahn’s past surfaced or garnered new attention, including another alleged sexual assault in Paris and an affair with a subordinate at the IMF. He has yet to offer his account of the sexual encounter with Ms. Diallo, except to insist (through his lawyers) that it was consensual. Mr. Strauss-Kahn emerges with little claim on the public’s sympathy, but he does emerge a legally innocent man, which, under the circumstances, is as it should be.