CONCORD, N.H. — The criminal case against Genevieve Kelley, a New Hampshire woman who absconded to Central America with her 8-year-old daughter more than a decade ago, is about to head to trial.

Custody cases that cross international borders are not uncommon and create a unique and challenging set of circumstances for parents and governments alike. Here are some things to know about international custody abductions and efforts to address the issue:

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THE NUMBERS

The U.S. State Department estimates at least 8,000 American children were abducted by a parent between 2008 and 2013, and legislation signed into law last year says more than 1,000 are reported each year. The department's Office of Children's Issues says it has received thousands of requests since 2007 for assistance in getting a child returned to the United States after they've been wrongfully abducted by a parent. Only half the children abducted to countries who participate in an international treaty are returned to the United States.

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INTERNATIONAL ATTENTION

The Hague Conference on Private International Law in 1980 recognized international custody abductions as a problem requiring a global response. Currently 93 countries, including the United States, have signed onto a convention that signals their desire to protect children from wrongful removal and to ensure their prompt return to their home country. The convention was not in play during the Kelley case, because investigators could never determine with certainty where she was.

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OBSTACLES

U.S. Rep. Chris Smith, a New Jersey Republican, has led efforts to reform the way the U.S. deals with international custody cases. His spokesman Jeff Sagnip says diplomatic pressures make it delicate for governments to negotiate deeply personal and often wrenching custody cases. With things like trade, aid or public perception at stake, governments can be reluctant to push the issue, Sagnip said.

For example, in one case championed by Smith, Brazil signed the Hague convention, but lawyers were able to delay the proceedings for years. Then there's the sheer logistics: Traveling back and forth for hearings and other legal wrangling puts an enormous financial strain on parents.

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PROMINENT CASES

Two recent cases have made international headlines, and one spurred changes in the way the United States deals with international abductions.

Smith helped secure the return of Sean Goldman to his father, David Goldman, in December 2009. Sean Goldman was taken to Brazil in 2004 at the age of 4 by his mother, who then announced she was staying in Brazil. She later divorced David Goldman and remarried. The boy's stepfather had temporary custody of him in a case that strained relations between Brazil and the United States.

In Vermont, a woman fled the country with her daughter in 2009 to avoid sharing custody with her former partner. Lisa Miller renounced homosexuality, ended the civil union she had entered into with Janet Jenkins in 2000 and took their daughter to Central America. Miller, a Virginia businessman and a Mennonite missionary are charged in a federal indictment with international parental kidnapping and conspiracy.

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CONGRESSIONAL ACTION

In July 2014, Congress approved Smith's bill that seeks to prevent international parental child abductions. The legislation, signed by President Barack Obama, requires the U.S. State Department to produce an annual report that names countries in which there was at least one parental abduction the preceding year, with the goal of shaming them into action.

The legislation also for the first time sets a schedule of actions, ranging from a private, unofficial complaint up to potential economic sanctions. The legislation also puts pressure on the State Department and the members of Congress who represent a parent to act.