Between the late 1920s and the onset of World War II, she travelled widely in Europe and North Africa promoting Zionism at conferences.
From the 1920s in particular, she fought passionately for the right of women to work and vote [only realised in France 27 years after other major European nations[4]].
In contrast to her feminist credentials, Netter was one of the advocates who successfully defended the Fédération Féminine Sportive de France against Violette Morris, a world-class French athlete, who was banned from competing or earning from her sports primarily because of her usual style of dress (wearing trousers).
"[8]In 1940, shortly after the defeat of France to the Nazis, Madeleine Fauconneau du Fresne – an activist for the Moral Re-Armament movement begun by Frank Buchman – was advised by a friend to engage the services of Netter after she was called to court to answer charges of defamation following an argument with a neighbour.
For the same reason, she was arrested on 4 July 1942 by French police and a Gestapo agent and interned at fr:Caserne des Tourelles.
Fauconneau Du Fresne had been arrested for arranging Netter's escape and was interned for several months in Beaune-la-Rolande wearing a white Star of David marked "Friend of the Jews".
When freed by the on 11 June by the préfet de Loiret (for lack of evidence), she joined Yvonne Netter and went to Toulouse with her, remaining with her brother until 1943.
Netter was in hiding until Paris's liberation, but despite this was part of the Comet Line resistance group as a liaison officer from July to December 1943 and from June to August 1944.