rule (something) out of court
To dismiss something completely and outright. Often used in passive constructions. Their comments may seem extreme, but we can't rule them out of court—they're still representative of a portion of the population that needs to be represented politically. A lot of the rules my English teachers told me back when I was a student have been since ruled out of court as being too stuffy or formal.
rule/throw something out of ˈcourt
make something not worth considering; completely reject or exclude something: The committee ruled any further discussion out of court.My suggestion was ruled out of court because it was too expensive.