It is used when someone claims to be something, and the other person nullifies his claim. It's like saying they are a liar and that particular thing doesn't have anything to do with him or her.
A: I am the custodian of democracy.
B: Democracy is innocent of you.
(Democracy has nothing to do with you, you're lying.)
A: I am a patriot.
B: Patriotism is innocent of you.
Is there an English equivalent that expresses this idea?