Something (bovine) Beyond Criticism

Word Meaning:

SACRED COW — (idiomatic) Something which cannot be tampered with, or criticized, for fear of public outcry. A person, institution, belief system, etc. which, for no reason other than the demands of established social etiquette or popular opinion, should be accorded respect or reverence, and not touched, handled or examined too closely.

Definitions from Wiktionary.