The Torah outlines twenty-four gifts, which the Jewish people are obligated to give the Kohanim. The simple rationale for these Misvot is to serve as a means of financial support for the Kohanim, who were constantly engaged in Torah and divine service. However, the Seforno (Ovadia ben Ya’akob Seforno, 1475-1550, Italy) offers a deeper explanation by which these gifts serve as a bridge to forge a connection between the masses and the spiritual leadership. Without them, each group would live and work separately. Due to these Misvot, each time a person sheared his sheep or kneaded his dough, he had to go visit the Hachamim and give them the gift. Through this interaction, the Hachamim were able to influence and teach those who otherwise would have no connection with them.
One of these gifts is separating dough, known as Halla, and giving it to the Kohen. The Pasuk states that the original Misva from the Torah only applies when the Jewish people live in the land of Israel. The Talmud understands this to mean that the entire nation must live in Israel in order for the Torah law of Halla to be in effect. Therefore, today, the Misva of Halla is M’drabanan (by Rabbinic law). Similarly, the Misva of Halla is always M’drabanan outside the land of Israel.
With regard to reciting a Beracha, there is no difference whether the Misva is commanded by the Torah or by the Hachamim. There are many instances of Misvot M’drabanan, such as Hanukah candles and Megila reading, upon which a Beracha is recited.
However, there is a significant Nafka Mina (practical difference) that results from Halla being M’drabanan. The following case occurred several weeks ago. A woman kneaded a quantity of dough that mandated separating Halla. (The standard minimum measure is 1.66 Kilograms, about 3.5 pounds.) She then separated a piece of dough and designated it as Halla, saying "Hareh Zo Halla." She put it aside. While she went to bring a piece of aluminum foil to burn the Halla, her housekeeper came and noticed the stray piece of dough and combined it back into the main mass of dough. The woman discovered what happened and called to ask what is the Halachic status of her dough.
In order to nullify the Halla recombined in the mixture, the permitted dough must be at least 100 times more than the forbidden Halla. For example if the main dough contained 2000 grams and the Halla separated was 50 grams, the entire mixture is forbidden for consumption. She would require a mass of 5000 grams to nullify the Halla, which she does not have. The problem was exacerbated by the fact that this occurred on Friday afternoon, close to Shabbat.
The easiest Halachic solution to this problem is to prepare and additional quantity of dough measuring the balance needed to reach 100 times more than the Halla. In this case, she could prepare another batch of 3000 grams and combine it with the original dough, achieving the necessary 5000 grams to nullify the forbidden dough. Generally, there is a prohibition of "En Mevatlin Issur L’hathila"-one is not allowed to intentionally add to a mixture in order to nullify forbidden content. How then is it permitted to add the extra dough? The answer is that this restriction applies only to Torah prohibitions; however, in Rabbinic prohibitions, such as Halla in our times, there is no problem. Thus, there is a practical ramification to the fact that Halla in our day is D’rabanan.
Theoretically, there could be another solution to this problem. If she were to appear before three men who would serve as a Bet Din (Rabbinic Court), she could perform "Hatarat Nedarim," and overturn her declaration designating the dough as Halla. That declaration has the same status as an oath. The only problem with this is that it would retroactively render her Beracha on the Halla a Beracha L’Vatala (a blessing in vein). Therefore, the first solution is preferable.
SUMMARY
The Misva of separating Halla is M’drabanan (rabbinically ordained). Therefore, the prohibition of intentionally nullifying a forbidden piece of Halla that was recombined into the dough does not apply.
