In Devarim, Perek Lamed Bais, posuk gimmel, the posuk teaches us that when we call out Hashem’s name we must bring greatness to Hashem. We learn from this halacha that one must recite Birchas HaTorah before he learns.
There is a discussion in Shulchan Aruch, Orach Chaim, siman mem zayin, seif zayin discussing what the halacha is if one forgets to say Birchas HaTorah. Can he be yotzei when he says the bracha of Ahava Rabba/Ahavas Olam? The question in Shulchan Aruch is whether it is sufficient for one to say Krias Shema and suffice that as learning, or is one required to learn Torah right after davening for the Birchas HaTorah to be effective.
Why shouldn’t Shema be sufficient? Isn’t a person yotzei the chiyuv of limud haTorah by saying Shema?
Rav Shteinman zt”l answered that we see there is a machlokes in the Gemara in Brachos, daf yud alef, amud bais when one needs to say Birchas HaTorah. The first opinion says only upon reading pesukim in the Torah. The second opinion says even upon Midrash. The third shitta holds even upon learning Mishna. One thing is for sure; according to every shitta one is mekayem the mitzvah of learning Torah whether he says a posuk, a Midrash, or a Mishna. The machlokes is concerning what triggers a chiyuv of Birchas Hatorah. One opinion is only reading a posuk, the other is even learning Midrash, and the third opinion is even learning Mishna. Likewise, we find in Shulchan Aruch, siman mem zayin, seif daled that if one is just thinking in learning, he does not need to say Birchas HaTorah. The Gra asked why isn’t someone yotzei the mitzvah of learning Torah while thinking in learning? The Chayei Adam says that since we learn from the posuk of “ki shem hashem ekra” that one needs to say Birchas HaTorah, it would only apply when one speaks with his mouth. However, in the case where there is just “hirhur,” (thinking) then one would not say Birchas HaTorah, despite the fact that he is mekayem the mitzvah of learning. With this understanding we can explain why Krias Shema would not be enough despite the fact that one is yotzei the mitzvah of learning Torah by saying krias shema, yet the Torah did not say one should recite Birchas HaTorah in a case where one learns in middle of davening.
Reb Chaim Kanievsky went to sleep very late one night. After saying Hamapil he found that he could not fall asleep. He got up and decided to learn. The question he had was whether he was required to say Birchas HaTorah or not? Was the fact that he said Hamapil a sign that he finished for the day and therefore a new day started when he got up? Perhaps that wasn’t so? Reb Chaim thought for a few minutes and decided that since Birchas HaTorah is a De’Oraysa, he was machmir and said the bracha of Asher Bochar Banu which the Shaagas Aryeh says is the only bracha of Birchas HaTorah one should say if he has a safek if he is chayev or not.
Why is the fact that Reb Chaim did not stop thinking in learning considered enough to show that there was no hefsek in his learning and therefore Reb Chaim should not need to say Birchas HaTorah? The answer could be that since one may not speak after Hamapil, for the purpose of Birchas HaTorah it becomes a hefsek because one cannot learn with speaking at that point.
Reb Chaim was asked, what should a person do if he forgot to count sefira and he already said Hamapil? Reb Chaim said he should wait until the morning and then count without a bracha. Why is this different from saying Birchas HaTorah? Why is he required to say the bracha if he wants to learn? Reb Chaim answered that regarding Birchas HaTorah, the person wants to stay up more and learn, whereas the person who didn’t count sefira wants to go to sleep as soon as he counts. He therefore needs to wait until the morning. (Reb Chaim joked about this and said that the sevara is flawed because how could someone fall asleep after knowing he will lose the zchus of making the bracha of sefira!)