Translate the following English sentence to French:
"However, those who, as a matter of course, only ever lay responsibility for crimes against humanity at the door of their political opponents, are committing the fatal error of simply using those very crimes to absolve themselves of all blame."
Pourtant, ceux qui, automatiquement, attribuent la responsabilité de crimes contre l'humanité à leurs seuls adversaires politiques commettent l'erreur majeure de n'utiliser ces crimes que pour s'exonérer de toute responsabilité.