is considered beyond reproach
beyond reproach Blameless, faultless, as in Jean's conduct at school is beyond reproach. The phrase employs the verb to reproach in the sense of "censure or rebuke," a usage dating from the early 1500s.
— The American Heritage® Dictionary of Idioms by Christine Ammer
reproach — [...] reprochen "to rebuke, reproach," from Anglo-French repruchier, Old French reprochier "upbraid, blame, accuse, speak ill of," [...]
— etymonline.com
EDIT: Originally this answer was simply beyond approachreproach though, as commenters said, this implies subject is in fact perfect, hence added the prefix "is considered" as suggested by @jasper