Madonna and ex-husband Guy Ritchie should try to settle a trans-Atlantic legal dispute over the future of their 15-year-old son Rocco and focus on enjoying what is left of his "precious" childhood, a High Court judge in London has said.
Mr Justice MacDonald said it would be a "very great tragedy" if more of the "fast receding" days of Rocco's youth were taken up by litigation.
The judge warned the singer and the film-maker that "summer does not last forever" - and said their child would "very quickly" become an adult.
He pleaded with them to resolve their differences in a ruling on the latest stage of litigation following a hearing in the Family Division of the High Court in London.
A lawyer specialising in family cases said Mr Justice MacDonald's comments would be a "reality check" for Madonna and Mr Ritchie.
Madonna and Mr Ritchie had married in December 2000 and divorced nine years later, the judge had heard.
They had agreed that Rocco would live in the USA with Madonna but spend time with Mr Ritchie.
A family court judge approved that agreement.
Difficulties had arisen shortly before Christmas.
Rocco had been due leave his father's home in London and return to his mother in New York.
But he had not gone back - and remained in the care of Mr Ritchie, said the judge.
Madonna wanted Rocco back in the USA and had launched family court action in London and New York.
Mr Justice MacDonald ruled on Monday that Madonna could halt legal action in England - and allow a judge in New York to make decisions.
Neither Madonna, Mr Ritchie nor Rocco were in court to see the judge deliver his ruling.
Rocco and Mr Ritchie had been at the hearing earlier this month but not Madonna.
Her lawyers had told the judge that she had wanted to attend but was on tour in Australia.
Madonna had accepted that a New York court had "jurisdiction", said Mr Justice MacDonald.
And he said "parallel proceedings" in two countries unnecessarily complicated matters.
But he said the best solution would be a negotiated agreement.
"At the root of these proceedings ... is a temporary breakdown in trust," said Mr Justice MacDonald.
"For all the media coverage, comment and analysis, this is a case born out of circumstances that arise for countless separated parents the world over.
"The court should always be the option of very last resort when parents cannot agree matters in respect of their children.
"Whilst the law provides a mechanism for the resolution of disputes between parents in respect of their children it is but a blunt instrument when compared to the nuanced virtues of calm discussion and considered compromise between those involved, accepting that this latter path can be a hard one on which to embark, and to sustain, in the context of relationship breakdown."
Mr Justice MacDonald said he, and Justice Deborah Kaplan - the judge overseeing hearings in New York, had repeatedly urged Madonna and Mr Ritchie to resolve the dispute.
He added: "I renew, one final time, my plea for the parents to seek, and to find an amicable resolution to the dispute between them.
"Because agreement is not possible today does not mean that agreement will not be possible tomorrow.
"Most importantly ... summer does not last forever.
"The boy very quickly becomes the man.
"It would be a very great tragedy for Rocco if any more of the precious and fast receding days of his childhood were to be taken up by this dispute.
"Far better for each of his parents to spend that time enjoying, in turn, the company of the mature, articulate and reflective young man who is their son and who is a very great credit to them both."
Specialist family lawyer Gemma Vines, who is based at law firm Wedlake Bell, said: "Mr Justice MacDonald's comments ... about the importance of finding a non-court based family solution highlights the pragmatic approach of the English court in relation to children cases and will no doubt provide a sobering reality check."