expression, godan verb (-ru)
set a bad example; create a bad precedent
Idiomatic expression derived from Mencius; used when someone's action establishes an undesirable model that others may follow. Often carries a cautionary tone.
彼の不正を許せば、俑を作ることになる。
If we overlook his misconduct, it will set a bad precedent.
An easy compromise could create a bad example.