When a Non Jew does something it would work according to Halacha, however when a Jew does the same thing it is useless.

5 Answers 5


Negating an avoda zara. If a non-Jew takes an idol and says "I reject this!" and damages it, the idol is no longer prohibited from benefit. A Jew can't do that.


If an animal was mostly slaughtered by a Jew (the majority but not all of the trachea & esophagus were cut) and the animal is not dying, a non-Jew can kill it however he wants and the animal will be kosher. If a Jew shechted the rest of the way, it would be a shihiyah b'miut batra (a pause in the final portion) and the animal is neveila (not kosher). But since the slaughter of a non-Jew is nothing, the majority slaughtered by the Jew is all that counts.

(See Shulchan Aruch YD 23:5)

  • Welcome to Judaism.SE, and thanks very much for that fascinating bit of Halacha!
    – Isaac Moses
    May 12, 2011 at 17:09

If a non-Jew does m'lacha for himself on Shabas, a Jew can use the result immediately; not so if a Jew does. (As always, CYLOR.)


A non-jew can taste a mixture of food to tell if the prohibited substance (e.g. milk in meat) inside gave taste.

  • 3
    If a Jew did so for some reason (e.g. he had a blood-sugar emergency), we would trust him, just as an Ashkenazi can trust a Sefardi who trusts a non-Jew, or we can taste a fleishig-sliced onion for meatiness.
    – Shalom
    Oct 5, 2010 at 23:03
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    Avoda Zara the non jew changes the status - by tasting food the jew still is the one who determines whether the food is Kosher. Oct 6, 2010 at 2:30

A non-Jew can run a kosher establishment without the certifiers worrying (as much) about him owning chametz over pesach, toveling all the kelim, etc..

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