The French are still reeling from their World Cup turmoil when players went on strike after Nicolas Anelka was sent home in disgrace.
Sagna said: "It's sort of a good behaviour code.
"We shouldn't need it but I was ashamed for the French people during the World Cup. A new era is beginning now."
New boss Laurent Blanc has given his squad the words of the French national anthem - to make sure they can sing it before facing Belarus in Paris tonight.