If a person separated food on Shabbat in a manner that is forbidden by Halacha – for example, he removed the undesirable substance from the desirable substance, as opposed to removing the food he desires from that which he does not want – the food, seemingly, should be forbidden for consumption on Shabbat. Just as food that is cooked on Shabbat in violation of Halacha is forbidden to be eaten on Shabbat, food that has been separated in forbidden fashion on Shabbat should, at first glance, be forbidden for consumption.
Hacham Ovadia Yosef, however, in his work Leviyat Hen, proposes an argument for permitting the consumption of such food on Shabbat. If a person would have simply taken the Ochel (desirable food) from the Pesolet (undesirable substance), rather than the other way around, the food would have been permissible. Hence, since there was a permissible way of separating the food, the Shabbat violation that one committed did not, in truth, have any effect on the food. As opposed to the case of raw food which one cooked on Shabbat, in the case of Borer the food could have been prepared in permissible fashion, and thus the prohibition that was violated did not contribute to the food’s preparation. And thus, since the violation was not necessary, one who eats the food is not actually deriving benefit from a Shabbat violation. Moreover, Hacham Ovadia notes, as opposed to cooking, which transforms the nature of the food, Borer – separating – does not bring about any fundamental change in the food. And thus since the forbidden act of Borer did not really change the food, it should not become prohibited for consumption as a result of the forbidden act.
On the basis of these arguments, Hacham Ovadia concludes that if one violated the prohibition of Borer inadvertently, such as if he was unaware of the relevant Halachot, then the food may nevertheless be eaten, despite the Halachic violation that was committed.
Rabbi Moshe Halevi, in his work Menuhat Ahaba (vol. 2, 7:10), goes even further, proposing a solution even for cases where one violated the Borer prohibition intentionally. Quite simply, he says, one may mix the two substances together again, and then separate them in permissible fashion – by removing the desirable food from the undesirable substance. The food is then permissible, because it had been separated in permissible fashion. Some authorities disputed this ruling, claiming that once food becomes forbidden for consumption, it cannot then become permissible. However, Rabbi Moshe Halevi cites Halachic authorities who allowed mixing the foods back together after they were separated, and then separating then anew in permissible fashion, and this is the view that is accepted as Halacha.
Summary: If one mistakenly separated foods in prohibited fashion on Shabbat, by removing the undesirable substance from the desirable food, the food is nevertheless permissible for consumption. If one separated food in forbidden fashion in willful violation of Shabbat, the food may be mixed back together and then separated anew in permissible fashion, and then becomes permissible for consumption.
