Another restriction of kashrut, which is followed very strictly by some Jews, less so by others, is the law concerning wine produced or handled by a non-Jew.
The prohibited use of any wine that a non-Jew produced for idol worship libations. The Rabbis extended this ban not only to wine produced by a non-Jew, but also to any Jewish-made wine that was touched or handled by a non-Jew. This was done to discourage social contact.
In the medieval period, when the Jews of France were deeply involved with their non-Jewish neighbors in the wine industry, many of these laws were reexamined. Moreover, by that time the use of wine for idol worship was very rare. Thus, certain rabbinic authorities permitted Jews to deal in stam yainam, as non-Jewish wine was called.
Nevertheless, the restriction on drinking still obtained, for the social reason. The Shulchan Aruch (sixteenth-century code of law) stressed that the prohibition is enforced to prevent drinking and social contact between Jews and non-Jews. This, it was felt, would lead to intermarriage.
Today, some authorities permit use of Jewish wine handled by non-Jews as long as it has been pasteurized (boiled during its production process). The reason for this is that the original prohibition exempted boiled wine, which was not used for libations or social drinking.
On the other hand, some authorities forbid wines that are touched even by a non-Sabbath-observant Jew. Most Orthodox Jews drink only kosher wines, which are simply wines produced by Jews under rabbinic supervision. These wines are generally packaged under double seals to prevent any prohibited form of handling.
The prohibition extended to any by-product of grapes, such as grape juice or grape jelly. However, it did not extend to whiskey, for whiskey is a grain product; it wasn’t used for idol worship purposes, so there was nothing on which to peg a prohibition.
Thus it is that there are times when Orthodox Jews drink kosher wines and regular whiskey in “mixed” company, but you won’t catch them eating pure grape candies that have no kosher label.