Members of Kabir Kala Manch, charged in 2011 under counterterrorism laws, remain subject to prosecution for their alleged support of Maoist militants.
One of them, eight months pregnant, was denied bail and must wait until Thursday for an appeals decision on her bail application.
Indian courts have repeatedly ruled that ideological sympathy should not be interpreted as active membership in a banned organization.
"The Indian authorities should not conflate shared sympathy for concerns about oppression and social inequity expressed by the Maoists with criminal complicity in violence," said Meenakshi Ganguly of Human Rights Watch.
"The government should ensure that peaceful activists can speak out without fear of terrorism charges."