The Halachic prohibition of "Hametz She’abar Alav Ha’pesah" establishes that no one may derive benefit from Hametz that was in a Jew’s possession during Pesah. If a Jew kept Hametz in his possession during Pesah, that Hametz is forbidden for all Jews even after Pesah, by force of Rabbinic enactment. According to Torah law, this Hametz is permissible. Once Pesah has ended, there is no longer any prohibition of Hametz, and it should therefore be permissible to eat, sell or derive any other kind of benefit from Hametz, regardless of where it was or who owned it during Pesah. However, the Sages imposed a penalty upon one who kept Hametz in his possession during Pesah – and, in effect, upon all Jews – and forbade deriving benefit from Hametz that was under a Jew’s possession during Pesah.
Therefore, a person who owns a warehouse or store containing Hametz must ensure to sell all his Hametz to a gentile before Pesah. Otherwise, he will not be allowed to sell the Hametz products even after Pesah.
An interesting question arises in a case of somebody who lives in New York and travels to Israel for Pesah. Before leaving, he goes to his Rabbi in New York and appoints the Rabbi as his agent to sell his Hametz to a gentile on his behalf before Pesah. The sale is usually performed at around 9 or 10 am on Ereb Pesah in New York. However, the prohibition of Hametz takes effect in Israel several hours earlier, because of the different time zone. The time in Israel is generally seven hours ahead of the time in New York, and thus when the Hametz prohibition takes effect in Israel at approximately 1 pm Israel time, it is still early in the morning in the New York, and the sale of this traveler’s Hametz has not yet been effectuated. The question thus arises as to whether the determining factor is the location of the individual, or the location of the Hametz. If the determining factor is the location of the Hametz, then the sale is perfectly valid, since it takes effect before the time when the Hametz prohibition takes effect. If, however, the determining factor is the location of the individual, then he is in violation of the Hametz prohibition once the prohibition takes effect in Israel, since his Hametz in New York has not yet been sold. And, his Hametz would thus be forbidden even after Pesah, due to the prohibition of "Hametz She’abar Alav Ha’pesah."
This issue is subject to a debate among the Halachic authorities. The work Oneg Yom Tob ruled that the prohibition takes effect based upon the location of the Hametz, in which case one may sell his Hametz in New York even though he will be traveling to Israel. The Hesed Le’Abraham, however, ruled that the prohibition takes effect based upon the location of the individual, and therefore the traveler in this case transgresses the Hametz prohibition once the prohibition takes effect in Israel, since his Hametz is still in his possession at that point.
No definitive ruling has been reached regarding this issue. Therefore, one who plans on traveling to Israel for Pesah must inform the Rabbi of his travel plans when he approaches him to arrange Mechirat Hametz. The Rabbi must then ensure to sell the Hametz already on the 13th of Nissan, the day before Ereb Pesah, so that the Hametz will leave the individual’s possession before the Hametz prohibition takes effect in Israel. If, however, this was not done, and the individual’s Hametz was sold together with everyone else’s Hametz on Ereb Pesah, after the time when the Hametz prohibition took effect in Israel, the Hametz nevertheless becomes permissible after Pesah. As mentioned, the status of the Hametz in such a case is uncertain, and since we deal with the Rabbinic prohibition of "Hametz She’abar Alav Ha’hametz," as opposed to a Torah prohibition, we may follow the lenient ruling. The principle of "Safek De’Rabbanan Le’kula" establishes that we may assume the lenient possibility in situations of uncertainty regarding a Rabbinic prohibition. In this case, then, since what’s at stake is a prohibition enacted by the Sages, we may follow the lenient possibility and permit the Hametz for consumption after Pesah.
Of course, this problem arises in the reverse situation, as well, when an Israeli resident travels to the United States for Pesah. His Rabbi in Israel buys back the Hametz from the gentile soon after Pesah ends in Israel, well before Pesah ends in the U.S. If the Hametz prohibition depends upon the individual’s location, then the traveler will be in violation of this prohibition, and his Hametz will be forbidden even after Pesah. Rav Moshe Feinstein (Russia-New York, 1895-1986) ruled that in such a case the Rabbi in Israel should buy back the person’s Hametz and then keep it for himself, as his own property, until Pesah has ended in the U.S. This way, the Hametz does not return to the individual’s possession until Pesah has ended in his current location.
It thus behooves everyone to clarify to the Rabbi while arranging the Mechirat Hametz where he will be during Pesah, so that the Rabbi can schedule the sale or the repurchase of the Hametz accordingly.
Summary: One who plans on traveling overseas for Pesah must inform the Rabbi of his plans when he goes to him before Pesah to arrange the sale of his Hametz, so that the Rabbi can ensure that the Hametz will be sold at the time when the Hametz prohibition is in effect in the traveler’s location.
