To kvinner står for en fransk domstol tiltalt for å ha brutt forbudet mot niqab i det offentlige rom.
Hind Amas and Kenza Drider were caught wearing the niqab in public outside Meaux town hall, eastern Paris, in May.
They could become the first of 91 women stopped by French police to be handed the 150 euro (£130) fine.
Campaigners say if a fine is imposed they will appeal against it all the way to the European Court of Human Rights.
Thursday’s sentencing in Meaux will be closely followed not just here in France but probably right across Europe.
Belgium, Italy, Denmark, Austria, the Netherlands and Switzerland all have - or are planning - similar legislation.
Divorced mother Amas, 32, who will be sentenced with fellow campaigner and mother-of-three Drider, has become a champion for several hundred women in France who insist wearing the niqab is a personal choice and a right enshrined by European law.
Hind’s parents were not strict Muslims. She put on the niqab for the first time six years ago as an educated single woman.
She claims she once wore mini-skirts and liked to party before she rediscovered her faith.
BBCs Christian Fletcher kommer med tilleggsopplysninger om at en en rik person vil betale alle bøtene til kvinner som blir bøtelagt for å være iført niqab. En av kvinnene skal dessuten gå med planer om å stille til presidentvalget, slik at hun vil stille til debatter med politikere i full mundur.
Det kan bli en politisk provokasjon med uforutsette konsekvenser. Trolig vil Marine Le Pen vinne mange stemmer på en slik strid.