It has been widely reported that Hamas engaged in widespread sexual violence on October 7th. Hamas however denies these claims and they have been been criticized by some independent sources (1, 2, 3). Most reasonable observers (e.g., UN) believe that these claims are plausible but warrant further investigation.
It would be interesting to study prior alleged instances of Palestinian sexual violence. Thus, if a precedent for this kind of conduct can be established, the claims could prima facie have greater merit.
In February 2019, a 19-year-old Israeli woman Ori Ansbacher was raped and murdered by Arafat Irafaiya, a Palestinian affiliated with Hamas. However, it is interesting to note Hamas' response.
Militant Palestinian groups, including Hamas and Islamic Jihad, condemned the killing after it was revealed that Ansbacher had been raped before her murder. Irfaiya received no legal representation from Palestinian Prisoners Club or other supporting groups. A senior Fatah official imprisoned in Israel also condemned the murder, expressing condolences to Ansbacher's family and asserting that there was nothing nationalist about Irfaiya's actions. He deemed the incident "an embarrassment to the Palestinian people" and stated that any attempt to place Irfaiya among Fatah prisoners would be resisted. Fatah had requested the Palestinian Authority not to provide Irfaiya with a monthly stipend or fund his defense.
This seems to suggest that rape of Israelis is something Palestinian militant groups are generally opposed to, as in this instance they condemned this crime (despite usually being in favour of attacks on Israelis). This could undermine the thesis that Hamas used rape as a systematic weapon on October 7th.
On the other hand, if there are other cases where systematic rape was used by Palestinians as a weapon of war, perhaps that would support the opposing argument.
Have Palestinians militant groups as a systematic policy engaged in, planned, supported or abetted rape in the past?
The "systematic policy" part is key here. In any military force, including even moral armies like the US military, there are likely a handful of "bad apples" who engage in heinous acts like rape during war time. However, this is generally not reflective of the military culture in general.