Observations: Hearts of gold and no hint of violence: a fresh look at les flics

One of the most striking moments in Polisse, the new film from French actor-director Maïwenn, comes when Fred, the hardest cop in the Parisian Child Protection Unit (CPU), consoles a boy who’s been forcibly separated from his mother.

In a film full of harrowing scenes – of paedophilia, incest, teen abortion – it stands out for its revelations about Fred's character. He's not just tough; he's compassionate, too.

Maïwenn's film, for which she spent time shadowing the real CPU, won the Jury Prize at Cannes 2011, and is released in the UK this week. It portrays les flics as sensitive, committed professionals, doing their best under immense logistical and psychological pressure: the CPU lacks the resources or prestige of the vice and homicide departments, yet often has to deal with the most distressing crimes. "They're not motivated by money," explains Maïwenn, ex-partner of Luc Besson (pictured). "They're there for the children. I felt honoured to witness their devotion."

And yet, she says, not everyone in liberal France was comfortable with her interpretation. "By showing the police in a sympathetic light, you can lose the support of a certain well-meaning, well-to-do, left-wing audience, who refuse to countenance tenderness towards the police."

British filmgoers' impressions of Parisian police are indelibly coloured by Mathieu Kassovitz's 1995 classic, La Haine, in which officers torture two of the young protagonists for kicks. The excellent French crime series Engrenages (broadcast on BBC4 as Spiral) depicts police brutality as standard practice. Polisse, by contrast, is notable for its lack of physical violence.

Until recently, French police had powers to interrogate suspects for 48 hours without charges or a defence lawyer. But in 2011, when Polisse was already in the can, reforms were introduced to ensure every suspect is read his or her rights, and can ask for a lawyer be present at any interrogation. "I stayed in touch with the CPU," says Maïwenn, "and they tell me it's harder now; the lawyers are always interrupting, and it really disrupts the energy of an interview." What does it mean for the next series of Spiral?

'Polisse' is out now