The proceedings concerned twin girls born to unmarried parents in 2008. At the time of the birth the parents lived together in Mexico.
In 2009, the parents agreed that the father would move to the United States of America, and that they would put in place an arrangement to keep the girls in the United States of America in order to take advantage of education, medical help and government support. Ultimately, although on different sides of an international border, the parents’ homes were only a distance of 10 miles apart.
From May 2009 till the autumn of 2010 the children lived with the mother in Mexico from Monday to Wednesday and with the father in the United States of America from Thursday to Sunday.
In September 2010, the parents’ relationship deteriorated. The mother threatened the father with violence and for two months the father had no contact.
The shuttle custody arrangement resumed over Christmas / New Year, but contact became irregular in February 2011.
On 24 March, the father collected the children, agreeing to return them on 27 March. However, he texted the mother to advise that he would not bring the children back.
The mother petitioned for the return of the children.
The United States District Court for the District of Arizona dismissed the mother’s petition, finding the girls to be habitually resident in the United States of America at the time of their retention.
The mother appealed.