KABUL, Afghanistan - An 18-year-old runaway named Amina agreed two weeks ago to leave the women's shelter in which she had taken refuge in northern Afghanistan and go home with her brother and her uncle.

What happened next is a cautionary tale for two young people from Bamian province who eloped and are still in hiding, even as some activists are trying to persuade them to turn themselves in.

She had run away to avoid marrying a man her family had forcibly betrothed her to, and agreed to return only after her family had signed guarantees that she would not be harmed. For good measure, her father and brother repeated their vows on video camera at the Ministry of Women's Affairs in Baghlan province, and she left with them.

She never reached home. Hours after she got into her family's car, a gang of gunmen dragged her out of the vehicle and shot her to death, her brother and uncle later claimed.

Very few convictions

Whoever was responsible — the police blame the jilted fiancé's family, but women's activists accuse Amina's family of staging her killing — Amina became yet another victim of an "honor killing" to absolve some sort of family shame. Rubina Hamdard, a lawyer at a coalition of women's advocacy groups, the Afghan Women's Network, estimates that 150 cases of honor killing occur every year in Afghanistan, based on statistics kept over the past five years. Fewer than half of them are formally reported, however, and very few end in convictions.

It was just such a possible fate that prompted Zakia, 18, and Mohammad Ali, 21, to flee into hiding after they eloped in March, fearing that Zakia's family would kill them both because she had refused her father's choice of a husband.

Neither Amina nor Zakia and Mohammad Ali did anything against the law — or, more specifically, against two of the legal systems in effect in Afghanistan: the body of civil law enacted over the past decade with Western assistance, or the classic Islamic code of sharia that is also enshrined in law. Both protect the rights of women not to be forced into marriage against their will.

But in Afghanistan, an unwritten, unofficial third legal system has remained pervasive: customary law, the tribal codes that have stubbornly persisted despite efforts at reform. "In Afghanistan judges stick to customary law, forget sharia law, let alone civil law," said Shala Fareed, a professor of law at Kabul University.

Hamdard said: "In any society it's not just the law that shapes everything, it's the behavior of the judges, and how they interpret the law."

But in many places, judges are poorly educated, a situation that continues to exist, despite some $904 million in "rule of law" funding from the United States alone, between 2002 and 2010.