THIS story is of no material importance to Japan. It is the story of Jane. And it is a story of a very small, dark sliver of 20th century geopolitics that festers still.

Jane is an attractive, blonde 40-something Australian, resident for many years in Japan and a mother of three boys. She is also the victim of a rape. Jane is not her real name.

She is actually the victim of two violations. The physical one was committed on April 6th 2002 near the American naval base at Yokosuka by Bloke T. Deans, an American serviceman. He violently raped her in her car.

What Jane refers to as her “second rape” happened afterwards, when she reported the crime to the Kanagawa prefectural police. There, she alleges that she was interrogated for hours by six policemen, who mocked her. At a later meeting, they laughed and made crude sexual comments. She was initially denied medical treatment, water and food. Jane was denied a receptacle to keep a urine sample—key forensic evidence in a rape. After four hours, all she could do was relieve herself on a cold police toilet and cry. The police made no attempt to preserve sperm or DNA on her body.

Her torment at the hands of the police so amplified the trauma of the evening that she actually tried to dial emergency services to report that she was being held against her will at the station, but an officer ripped the phone from her hand. Ultimately she was kept in custody for some 12 hours following the crime, before having to drive herself home.

The police located the assailant, Mr Deans, of the aircraft carrier USS Kitty Hawk, but for reasons that remained unclear, no charges were filed against him.

Jane, however, filed and won a civil case against him: a Tokyo court ordered him to pay ¥3m (around $30,000) in November 2004. But unbeknownst to Jane or the court, soon after the suit was filed, the American navy had quietly discharged Mr Deans, who returned to America and disappeared. Later, she received compensation from Japan's Ministry of Defence, out of a discreet fund for civilian victims of crimes by American military personnel.

In Jane's view, the first rape went unpunished: Mr Deans remains at large. So she turned her attention to the “second rape”. She sued the Kanagawa police for a bungled investigation that denied her proper justice. In December 2007 the court ruled against her, stating that the police had fulfilled their responsibilities. She appealed the decision.

Jane's ordeal underscores the clumsiness of Japan's police force. In several recent high-profile cases, the police have coerced confessions from suspects. It also highlights the lack of a tradition of individual rights in the country, and the often thinly reasoned rulings of Japanese courts. And it fits the pattern that in many crimes by American servicemen, the Japanese authorities fail to press charges.

But the reason why cases like Jane's are not prosecuted may have less to do with incompetent police and more because of a secret agreement between America and Japan in 1953 that has recently come to light.

In September 2008, Shoji Niihara, a researcher on Japanese-American relations, uncovered previously classified documents in the U.S. National Archives. They show that in 1953, soon after Dwight Eisenhower assumed the presidency, John Foster Dulles, his secretary of state, embarked on a massive programme to get countries to waive their jurisdiction in cases of crimes by American servicemen.

On October 28th 1953, a Japanese official, Minoru Tsuda, made a formal declaration to the United States (not intended for public disclosure), stating, “The Japanese authorities do not normally intend to exercise the primary right of jurisdiction over members of the United States Armed Forces, the civilian component, or their dependents subject to the military law of the United States, other than in cases considered to be of material importance to Japan.”

In other words, Japan agreed to ignore almost all crimes by American servicemen, under the hope that the military itself would prosecute such offences—but with no means of redress if it did not.

This helps explain the perplexing, toothless approach of the Japanese police and prosecutors even today in cases of crimes by American military personnel. When Mr Niihara first made the documents public in October, a senior Japanese official denied any such agreement, but in words so mealy-mouthed that it raised suspicion.

Japan's landmark accord with the United States over troops stationed in the country, called the Status of Forces Agreement, was signed in 1960. Article XVII.1b states: “The authorities of Japan shall have jurisdiction over the members of the United States armed forces, the civilian component, and their dependents with respect to offences committed within the territory of Japan and punishable by the law of Japan.”

But in practice the Japanese do not exercise their authority. Jane's case was just one of many in which the Japanese authorities opted to look the other way. This has nothing to do with the specifics of her case; it stems from an intergovernmental security protocol negotiated a half-century earlier.

Why did America fight so hard in 1953 to maintain control of criminal cases involving its boys? The documents do not say, but provide a clue: in numerous settings, American officials express unease that American servicemen commit roughly 30 serious crimes each month. Having 350 soldiers sent to Japanese jails each year would have been bad for America's image. According to a separate document, America struck similar, secret agreements with the governments of Canada, Italy, Ireland and Denmark.

When Jane talks to reporters, she wears stylish, bug-eyed, mirrored sunglasses that seem more shields than fashion statement. It is futile protection—a tangible symbol of her quest for anonymity, akin to her pseudonymity.

On December 10th 2008, the Tokyo High Court ruled on Jane's appeal in the suit against the Kanagawa police. Judge Toshifumi Minami entered the court, told her “You lost. And the financial burden of the case lies with you,” and then left. A 20-page ruling, considered short, sheds little insight into how the court reached its decision. Jane plans to appeal to the Supreme Court. “I lost—but they lost too,” she said.

Jane will always bear indelible, invisible scars. But this is of no material importance to Japan. Or America.