Here is a concrete legal case handled by the rabbinical courts. We have chosen this example to help you learn, ponder upon and gradually assimilate "Daat Torah", so your mindset and reflections increasingly tune-in with the Torah.

Question

Mr. Israeli had three boys. He always refused to write a detailed will. However, he asked his eldest son David to renounce his birthright, so that his legacy be distributed in three equal parts. David agreed. After his father's death, David inherited a third of the money left in his late father's bank accounts.

The three sons let their mother profit from income on real estate assets to enable the widow to pursue a decent standard of living. Three years later, their mother passed away, leaving behind three apartments.

David claimed his share as an elder. He confessed to the Beth Din that he promised his father to renounce his birthright, but that he did so only to avoid annoying him. In addition, he argued that one cannot relinquish a future right.

But the brothers retorted they had evidence of David's consent to this relinquishment: he had accepted an equal division in the bank accounts.

Psak and Commentaries

David applied his birthright on half of the real estate. However, the other half was equally divided between the three brothers.

The Shulchan Aruch (278) states: a firstborn may inherit two parts of his father's property, but this right does not apply to his mother's assets. Even if he is the firstborn of another two siblings, he is bound to share the property equally with his brothers. Given that Mrs. Israeli owned half of the apartments, her share in the assets she bequeathed to her children was not bound by the rules of firstborn birthright.

The opinion of Ksot Hachoshen (id.13) is that a firstborn may relinquish his birthright while his father is still alive. He offers the example of Yaakov who bought his birthright from Eisav. But the Rivach (328) retorts that before the giving of the Torah, rules were different. According to the opinion of Ksot Hachoshen, David would have had to renounce his share. According to Netivot (id.), a firstborn cannot relinquish his rights during his father's lifetime.

This difference of opinion allowed David to enjoy his birthright. The court also weighed their decision based on the claim made by David that he relinquished his birthright to avoid displeasing his father.

On the other hand, it should be known that a firstborn who owns a shared property in equal parts completely relinquishes his birthright, as stipulated by the Shulchan Aruch (278-8). David having accepted to share the money secured in bank accounts in equal parts, should have consequently lost his birthright.

The answer is that the birth right does not apply to bank accounts because the latter are considered loans to the bank and not cash (on this subject, see Shulchan Aruch (id 7). See also responsa: Ginat Vradim Even Hazer Clal 4, 19 Yavets b; 31 Chaim Shaal 74, Yabia Omer 8, 8, Pitchei Hoshen chapter 2, 36, Shevet Halevi t.4, 215) concerning the status of money in the bank).