"If two men get into a fight with each other, and the wife of one comes up to save her husband from his antagonist and puts out her hand and seizes him by his genitals, you shall cut off her hand; show no pity." Deuteronomy.25.11
IIRC, Rambam learns from that verse that an aggressor should be stopped by all means. But in this case, the woman is protecting her husband who's attacked by another man.
Why should be such a woman be stopped by cutting her hand off?