A five-year-old boy must leave his English mother and return to Spain to live with his Moroccan father, a High Court judge has ruled.
Mr Justice Holman concluded that the woman had wrongfully kept the boy in England for more than a year in breach of an order by a Spanish court.
The judge was told that both parents had overcome "drug addiction problems" and heard that the boy's father, a handyman, had served a prison term after being convicted of drug trafficking.
He made a ruling after analysing the case at a hearing in the Family Division of the High Court in London.
The hearing was staged in public but the judge said nothing could be reported which might identify the child.
Mr Justice Holman heard that the man lived near Alicante and the woman on the south coast of England.
They had met in Spain about seven years ago and separated about two years later.
The man had been convicted of drug trafficking prior to the child's birth and had spent about five months in prison, the judge heard.
Mr Justice Holman said the boy had been born in Spain and a Spanish court, which had jurisdiction, had ruled that he should live in Spain with his father.
He said that order had to be enforced under international law.
And the judge said the woman had promised to obey the Spanish court order but had not obeyed it.
"He has got to go back," the judge told the woman. "In Spain, if you wish, of course you can make some fresh application for him to come and live here. But in the meantime he has got to go back."
Mr Justice Holman added: "You may think 'he is very tough', lacking in understanding. Far from it. I have huge understanding.
"But I also have understanding for the situation the father is in in Spain. He has not seen this child for however many months."
The judge said the woman could visit the child in Spain and see him in holidays.