We know where we are. Outside the Royal Courts of Justice there is a media scrum and the usual rentacrowd. Inside, a calm and authoritative judge of the Family Division announces her decision which means that one conjoined twin will die. Afterwards Mrs Justice Fiona Maye (Emma Thompson) leaves by a private door and walks, unnoticed, to her large Gray’s Inn flat. Here she can sit at her beloved piano, preparing for a Benchers’ Christmas party recital which will pair her with counsel who regularly appears before her. But her classicist husband, played by a charming and virile Stanley Tucci, interrupts with an announcement. Tired of 11 months of celibacy in his marriage to a workaholic, he wants to have an affair.

Except that morally we do not know where we are.

Ian McEwan has adapted his own novel for the screen. The ‘story’ is actually about another fraught case: should the judge allow a hospital to administer blood transfusions to save a 17-year-old leukaemia victim against the wishes of his parents, who are Jehovah’s Witnesses? McEwan has been quoted as explaining that this is based on a real case related to him by his friend, Sir Alan Ward, who is also legal consultant on the film. Sir Alan went to the boy’s bedside to test his resolve to die. After giving the hospital the order it sought he took the boy to a football game. Later he discovered that the boy’s illness returned but, now an adult, was permitted to refuse treatment and died.

"Anguished expressions are thick on the ground here, but McEwan endows the judge with a refusal to say anything. When stressed she can be difficult with her marvellous clerk but never apologises. She will not reply when her husband begs to discuss their marriage"

Things are much more complex here. The boy, Adam, is played by Fionn Whitehead, as handsome as he was in Dunkirk, highly articulate and even more highly strung. And talented – he plays a song on a guitar which the judge knows and they sing together. Who wouldn’t want to keep him alive? But what happens afterwards is not normal. Based on the one encounter, Adam becomes obsessed, indeed in love with the judge. Once restored to health, he relentlessly stalks her, writing poems, leaving messages on her mobile, and tracking her down to judge’s lodgings where he begs to come and live with her. He even manages a parting kiss.

Her reaction is proper. She sends him home. She does not, however, contact anyone who might sit him down and explain the judge’s role to him. For his part, Adam is aware that he is living with parents who were willing for him to die, a profound issue the movie skips over.

Anguished expressions are thick on the ground here, but McEwan endows the judge with a refusal to say anything. When stressed she can be difficult with her marvellous clerk but never apologises. She will not reply when her husband begs to discuss their marriage. He willingly sleeps apart from her for months, awaiting a change of heart, thus curiously shifting our sympathies to the adulterer. Does she somehow yearn for the boy as either the child she never had or the partner she’s rejected? Is this all a comment on the distressing workload which family judges take on? Who knows? When Adam gets sick and refuses treatment we have no idea why and he is too far gone by the time the judge melodramatically rushes to his bedside. At his burial she says, ‘I was cruel to him.’ Actually, she wasn’t.

Everything else in the movie rings true – the behaviour of everyone in and out of court and at hospital is wonderfully well done. ●

David Wurtzel practised at the criminal Bar for 27 years and is a door tenant at 18 Red Lion Court. Prior to his retirement, he was a consultant in the CPD department at City Law School and consultant editor of Counsel. David is a member of the Counsel Editorial Board.