What is the term for exercising one's public rights, often through speaking out in protest or in favor of some policy change?

political voice

Explanation:

Political voice is a characteristic of a democratic system that entails the right to every citizen of state to speak out on unfavourable policies that do not reflect collective views or contradict democracy in any way.

This works to boost participatory governments and ensure the government is more representative of the community or state that they serve.