Lying at their door - Idioms by The Free Dictionary
lie at (one's) door (redirected from lying at their door)
lie at (one's) door
To be one's responsibility. Typically said of something negative. I'm the coach, and I called a bad play, so any blame for this loss lies at my door.
lie at somebody’s door (formal) (of the responsibility for a mistake, etc.) belong to somebody: The main problem is the design of the building and the responsibility for that lies clearly at the architect’s door.