German Wikipedia refers to this authority as "closely watched" for abuse by public officials; there being reports of such abuse, but only a few of them; and it

German Wikipedia refers to this authority as "closely watched" for abuse by public officials; there being reports of such abuse, but only a few of them; and it being a "mostly symbolic" right. There are fifteen cases of killings known to us, and in almost all of them, the punishment would also have been due to other legal constructs. None of this contradicts anything you said, I'm just adding some context. Roman heads of family obviously weren't habitually killing relatives all the time. https://de.m.wikipedia.org/wiki/Patria_Potestas https://de.m.wikipedia.org/wiki/Patria_Potestas