speak up for (one)
To testify, argue, or give defense on behalf of one. Thank you for speaking up for me back there. I think the boss was ready to fire me! Our organization's goal is to speak up for the disenfranchised groups of the country.
speak up for someone or something
to speak in favor of someone or something. If anybody says bad things about me, I hope you speak up for me. I want to speak up for the rights of students.