The tragic mass shooting in Newtown, Connecticut, has drawn renewed attention to Jewish attitudes toward weapons and gun control policy. In a series of articles in Jewish Ideas Daily, I have tried to postulate what policies one might derive from Jewish law and values. This essay will focus on the level of responsibility a gun seller has for the way his customers use their weapons.The Talmud forbids selling weapons to pagans because they are prone to using them immorally. “One should not sell to idolaters either weapons or accessories of weapons, nor should one sharpen any weapon for them, nor may one sell them stocks, neck-chains, ropes or iron chains.”The writer teaches at Yeshivat Hakotel and directs the Tikvah Israel Seminars for post-high school students. Facebook.com/RabbiShlomoBrody.Some Sages even pondered whether one may sell protective gear, such as shields, to idolaters, because they might also be used for aggressive purposes. Ultimately, protective wear was excluded from the ban, but all agree that it is prohibited to sell raw materials that are used exclusively for making weapons. The Sages also added to the list of prohibited items wild animals or other beasts that threaten the public welfare.Medieval commentators gave various explanations for these regulations. Some were anxious that hostile neighbors would turn on the Jewish community and use these weapons against them; others more broadly feared the general destruction brought upon the world by the unethical use of weapons. Several noted that Noahide Law prohibits homicide and that as a general rule, Jews are proscribed from aiding and abetting in any sinful behavior.Based on this latter principle, the Talmud adds that one may not sell a weapon to a Jewish robber who we fear will use his weapon in the course of the intrusion. The Sages further prohibited selling weapons to scheming Jewish middlemen who would then sell them to these suspect gentiles. As such, is is clear that the notion that a salesperson may simply close his eyes to the harmful use of weapons is foreign to Jewish law. One may not sell a weapon to any person – Jewish or gentile – who one suspects will use it inappropriately.Yet the Talmud also notes that in Babylonia, Jews sold weapons to gentile neighbors who used them to protect their cities. Some medieval commentators deemed this a realpolitik dispensation: we need their help in protecting us, and hopefully they will not later use the weapons against us. Yet many medieval commentators understood this clause as a more principled statement: One may sell a weapon to someone with whom we have friendly relations and who we believe will use it responsibly, such as for the sake of self-defense. Of course, such evaluations are subject to time and place and will change in different societies.Writing in the first decade of Israel’s existence, Rabbi Yaakov Moshe Toledano (d. 1960), former chief rabbi of Tel Aviv and Israel’s religious affairs minister, prohibited Israeli gunshop owners from selling guns to local non-Jews (presumably from neighboring Arab villages) who he feared, based on past violent incidents and continued animosity, would come to use the weapons against Israel’s Jewish citizens. In contrast, the current head of Jerusalem’s rabbinic courts, Rabbi Eliyahu Abrizal, has asserted that in the contemporary climate, one is only prohibited from selling weapons to known criminals. Otherwise, gun sales remain permissible to Jews and non-Jews alike. Abrizal’s permissive stance seemingly relies on the assumption that the gun shop’s customers have legitimate intentions for their purchase, such as self-defense. He might further only be addressing the situation created by Israel’s relatively successful gun control regulations, leaving unclear what he would rule in a different country.Abrizal also buttresses his position with a significant legal caveat to the prohibition of aiding and abetting: one is only liable if the person would have otherwise been unable to purchase the item. If a gun (or other prohibited object) could be purchased elsewhere, then the seller is absolved from definitive responsibility. Many medieval Jews were involved in selling merchandise relating to Christian rituals, even as they would normally be forbidden from trading in another religion’s artifacts. Not all medieval decisors were comfortable with this principle, arguing that Jews remain culpable, albeit on a lower level, for aiding in other people’s sins, especially with regard to severe infractions like idolatry. Toledano and others have contended that no such dispensation applies when it comes to weapons sales, since a Jew is held liable for any role he played in helping someone commit bloodshed.Given the debate over the use of this dispensation, it remains difficult to allow Jews to sell weapons unless one can be very confident that local gun control regulations will ensure that the buyer will use them responsibly. This highlights the importance for Jews, both in Israel and around the world, to lead the call for gun control regulations that will allow for self-defense but do the utmost to ensure that weapons do not fall into the wrong hands.