The child, a boy, was almost 2 at the date of the alleged wrongful removal. The parents were married and had joint rights of custody. The father was a university professor. In December 1997 he was awarded a 12 month period of sabbatical leave which he intended to spend with his family in Europe. The family left Colorado on 1 August 1998. Until then, the child had spent his entire life in the United States.
For the first part of the sabbatical, until March 1999, the father had a teaching position at the University of Basel in Switzerland. The family then intended to spend 3 months in Austria and 1 month in Ireland, returning to Colorado in August 1999. In late 1998 the parents began to experience marital difficulties, both sought legal advice.
On 21 February 1999 the father returned to Colorado with his son. The mother then commenced divorce and custody proceedings in Switzerland, the father in Colorado. The mother subsequently petitioned for the return of her son on the basis that he was habitually resident in Switzerland at the time of the removal.