The Exemption of a Groom from Kriyat Shema
The gemara in Berakhot (16a) asserts that a groom is excused from saying kriyat shema for the first four nights after his wedding. This halakha is derived from the phrase, 'b'lekhtekha vaderekh' ('when you are walking on your way'), which excludes a chatan who is walking upon a different way (as he is mentally involved in the process of bi'at mitzva). As the gemara concludes, his preoccupation with a mitzva exempts him from kriyat shema. Someone who is occupied in only mundane matters (such as one who is worried about his business) does not enjoy this exemption.
The obvious explanation of this halakha would be the inability of this preoccupied chatan to reach the necessary levels of kavana. Unlike other mitzvot, which (bedi'eved) may be executed without deliberate kavana, kriyat shema requires concentration and consciousness – at least for several parts of its recitation. The gemara in Berakhot (13b) cites different 'cut-off' points but unanimously demands that kriyat shema be recited with kavana. As the essence of the mitzva is the embrace of theological principles, it cannot be fulfilled without an internal awareness. Preoccupied with the performance of another mitzva and unable to concentrate, the chatan is excused from kriyat shema since he cannot perform it anyway. Someone who is worried about personal issues is not given this same dispensation but is demanded to overcome his 'disruptions' and focus on kriyat shema.
This explanation, however basic, raises certain questions. First of all, if his exemption is based solely on his inability to concentrate, we might question the need for a pasuk. After all the gemara (13a, 16a) already derived the need for kavana during kriyat shema from different pesukim. It should be obvious that someone who has a legitimate excuse for not reaching these levels is automatically excused without the need for a special pasuk. Secondly the mishna (16a) cites a discussion between Raban Gamliel, who recited kriyat shema as a chatan, and his talmidim. The students questioned his practice in light of his having himself taught them the chatan exemption. Assuming the chatan clause is solely based on the technical inability of a chatan to concentrate, why didn't his students assume that Raban Gamliel was obligated insofar as he was able to focus on kriyat shema despite his preoccupation? In fact, Raban Gamliel does not even respond in this manner to his talmidim. He offers a slightly different reason for his conduct: "I cannot excuse myself from malchut shamayim even temporarily." His answer suggests that even he felt that he didn't perform the formal mitzva of kriyat shema, but recited the parshiyot anyway to help him maintain his religious and theological consciousness. Evidently, he agreed with his talmidim that even a chatan who is capable of concentrating can not properly fulfill kriyat shema.
These two factors - the presence of a pasuk excluding a chatan as well as the inability of Raban Gamliel to fulfill kriyat shema – suggest a different approach to the chatan exemption: this halakha might be fundamental, and not just technical (such as the inability to concentrate). The Torah might have determined that a groom's prior obligation to the halakhic experience of marriage exempts him from reciting shema. By conditioning shema as applying to someone who 'walks on the way,' (i.e. without alternate commitments) the Torah imposes kriyat shema only upon those who are not already obligated to a different and competing halakhic system. A chatan, who is already committed to bi'at mitzva – a mitzva which occupies him both mentally and physically - is excluded from kriyat shema at a fundamental level, not merely because he can't concentrate. This view would explain both the need for a special pasuk to outline the categorical exemption (rather than an assumed technical one) as well as the inability of even a 'focused' chatan such as Raban Gamliel to fulfill shema.
The question of how to understand the chatan exclusion might have already been implied in an interesting Tanaitic debate cited by the gemara in Sukka. The beraita (25b) cites the position of the Tana Kama who obligates a chatan in the recital of the first pasuk of kriyat shema despite his exemption from tefilla and tefillin. After all (as Rashi comments), it is not that difficult – even for a chatan - to focus upon the first pasuk of kriyat shema (which, according to most Rishonim, constitutes the mitzva d'oraita). Other mitzvot such as tefillin and tefilla, which require more extended periods of concentration, are not required of a chatan. In addition, the Tana Kama extends the tefilla and tefillin exclusion to ushers and other 'bnei ha-chupa' who are involved in the wedding ceremony. Evidently, the Tana Kama viewed this general exemption as technical in nature: inability to concentrate excuses one from a mitzva which requires concentration. Hence, the Tana Kama was willing to extend the category to a non-chatan, who is nonetheless preoccupied, while they required even a chatan to recite the one pasuk of 'Shema Yisrael' which doesn't demand excessive attention.
Subsequently, the beraita cites the position of Rav Shila, who exempts the chatan from kriyat shema but limits the exclusion to the chatan; the members of his wedding party are not excused. Conceivably, Rav Shila might have viewed the chatan exemption as categorical, rather than technical. Due to his prior commitment to another halakhic process, the chatan is fundamentally excused from kriyat shema - even from the first pasuk which would not require undue focus. However, as the exemption is based on a prior personal obligation to another mitzva, this clause cannot be applied to a non-chatan, even those busy assisting a mitzva. They can technically excuse themselves from that prior involvement.
This structural question would seemingly generate technical ramifications. Would a chatan be excused if he weren't necessarily preoccupied with bi'at mitzva? For example, the Ra'avad, in his comments on the Rambam (kriyat shema 4:1), claims that if the bride is ill or a nida (in which case sexual engagement will be delayed), the chatan must recite kriyat shema. The Ra'avad evidently operates with the notion that the actual immersion in the performance of the mitzva excuses a chatan from kriyat shema. Where this mitzva is suspended, the obligation of kriyat shema is re-established. By viewing the exemption as categorical we might disagree with the Ra'avad. Even though his wife is in a state unsuitable for the performance of the mitzva, the chatan still remains obligated to this mitzva and is hence excused from kriyat shema.
A related question might pertain to whether a chatan is excluded from kriyat shema during the day. The mishna in Berakhot (16a) discussed his exemption from kriyat shema for the first four nights. The Kessef Mishna (in his comments to the Rambam ibid.) cites two positions (one in the name of Rabbenu Mano'ach) as to whether this exclusion applies to daytime kriyat shema. He explains the position which does not extend it to the day as follows: since the day is not normally an occasion for bi'a, most Jews remove the experience from their mindset during the day and hence a chatan is free to focus on kriyat shema. Again, this position assumes that the exclusion from kriyat shema is based entirely on the reality that a chatan cannot concentrate. Once factors have delayed bi'a and, assumedly, he can adequately focus, his obligation is reinstated. By defining the exemption in more categorical terms, we might apply it even in contexts in which actual bi'a cannot occur but the chatan remains obligated to consummate that mitzva.
An inverse question might pertain to a chatan who might not be formally committed to the mitzva but who is still anxious and unable to concentrate. The mishna mentions the exemption as applying to the first four nights after the wedding. What happens if these four nights pass and the bi'a has still not occurred? Would the exclusion continue? Though the Me'iri in Berakhot quotes an opinion which does extend the exemption, most limit this clause to the four nights mentioned in the mishna. Most base their reasoning on the presumption that after four nights his anxiety diminishes (see, for example, the Rambam in his commentary to the mishna and the Rabbenu Yona on the gemara). They still view the exemption as based on his mental state and shape the halakha along these lines. Might we suggest that once the exemption is seen as nominal or categorical it can be formalized into four days (the standard window within which bi'a occurs), independent of the mental state of the chatan? Even if this particular chatan is still worried, after four days he is no longer legally defined as committed to the competing mitzva of bi'a, and is hence obligated to recite kriyat shema.
A parallel situation emerges from a discussion in the gemara in Ketuvot (6b) which cites a debate between Rava and Abaye as to whether the initial bi'a may take place on Shabbat evening (since the breaking of the hymen and the exit of blood might constitute a Shabbat violation). Rava seeks to prove from our gemara that indeed such bi'a may occur on Shabbat. After all, our gemara exempts a chatan from four nights of kriyat shema even though most weddings occurred Wednesday night. By excluding him from Shabbat kriyat shema, the mishna assumes that bi'a rishona may take place on Shabbat and, consequently, the chatan will be too anxious to say kriyat shema. Abaye answers that although he cannot perform bi'a rishona, he is still exempted because he is worried about having not yet performed bi'a. It is very notable that Abaye extends this chatan exemption to a chatan who is halakhically forbidden from bi'a (according to Abaye), being that he is still anxious. Rava might have maintained that his psychological state is not enough to exclude him from kriyat shema. If he does not possess the mitzva and is not obligated to a conflicting 'occupation,' he cannot be excused from kriyat shema. Hence, Rava is forced to assume that actual bi'a rishona may occur on Shabbat.
Whenever we isolate a halakha as based on two potential concepts, the logical nafka minot would be cases which exhibit one facet and not the other. This shiur probed whether the chatan exemption is based on his psychological anxiety or the formal obligation to perform the mitzva. Subsequently, we isolated instances in which he possesses a mitzva but no anxiety (Raban Gamliel, if his wife were a nida, or the daytime kriyat shema). We also studied instances in which he possesses this mental preoccupation but might no longer possess the formal mitzva (after four days or during Shabbat). These cases are potentially significant in determining the true basis of a halakha.