A Pure Formality (Italian: Una pura formalità) is a 1994 Italian-French drama thriller film co-written and directed by Giuseppe Tornatore.

It stars Gérard Depardieu as a reclusive writer and Roman Polanski as a police detective.

The Inspector (Polanski) is suspicious when Onoff is brought into the police station one night, disoriented and suffering from amnesia.

As the head of an isolated, rural police station the Inspector tries to establish events through careful interrogation and deduction.

Through his painstaking inquiries, he eventually clears up a mysterious killing and brings the writer to a new and unexpected realisation.