1) EXEMPTING A PERSON FROM A "CHIYUV MISAH" IN A CASE OF A DOUBT
QUESTIONS: The Gemara says that according to Rebbi Yosi, when the owner of an Eved sells his Eved to another master with the condition that the Eved will continue to work for him for thirty days, the law of "Yom O Yomayim" applies to both masters. Consequently, both masters are exempt from Misah if either one hits the Eved and he dies from his wound after one full day. The Gemara says that Rebbi Yosi's reason for exempting both masters is that he maintains that the Halachic status of a Kinyan Peros (the rights to the Eved's service) is in doubt; perhaps it has the status of a Kinyan ha'Guf (the ownership of the actual body of the Eved). Consequently, it is not possible to determine who the true owner of the Eved is, who should be exempt because of "Yom O Yomayim." Due to this doubt, the rule "Safek Nefashos l'Hakel" applies and both masters are exempt from Misah.
The RASHBAM explains that the principle of "Safek Nefashos l'Hakel" is derived from the verse, "v'Hitzilu ha'Edah" -- "and the congregation shall save" (Bamidbar 35:25), which teaches that Beis Din is obligated to try to exempt a person from a Chiyuv Misah and not to kill him (Sanhedrin 32b). This is also the way RASHI explains in Kesuvos (15a) and Bava Kama (44b). The Gemara there discusses a case in which a person throws a stone into a group of ten people, half of whom are Jews and half are Nochrim. Even if the stone kills one of them, the one who threw it is exempt because of "Safek Nefashos l'Hakel." Rashi explains that the law is lenient in a case of a Chiyuv Misah because of the verse, "v'Hitzilu ha'Edah."
Rashi's source seems to be the Gemara in Pesachim (12a) in which Rebbi Yehudah says that when two witnesses attempt to have a person put to death, and one of the witnesses says that the event occurred in the third hour of the day and the other witness says that it occurred in the fifth hour of the day, their testimony is accepted. The Gemara explains that it is possible that the event occurred halfway through the fourth hour, and a person is not so careful to clarify the exact time of an event by more than half an hour. The witness who says that the event happened in the third hour means that it happened in the end of the third hour (which is the beginning of the fourth hour), and he is off by just half an hour. The witness who says that the event happened in the fifth hour means that it happened in the beginning of the fifth hour (which is the end of the fourth hour), and he, too, is making a mistake of only half an hour. The Gemara asks how can Beis Din accept such testimony in order to put a person to death? Beis Din has not clarified the true intentions of the witnesses, and thus Beis Din remains in doubt about what they actually meant to say. A person cannot be put to death out of doubt because "Safek Nefashos l'Hakel"! The Gemara there adds, "and the verse says, "v'Hitzilu ha'Edah."
There are a number of questions on the explanation of Rashi and the Rashbam.
(a) Why does Rashi find it necessary to suggest that the verse is needed to exempt a person from a Chiyuv Misah? Logically, if there is a Safek if someone must be put to death or not, Beis Din certainly should not kill him out of doubt. Whenever there is a doubt about whether an obligation needs to be fulfilled (a Safek Chiyuv), one does not do a prohibited act in order to fulfill that Safek Chiyuv. For example, if a person has a garment and there is a doubt about whether it needs Tzitzis or not, and there is linen in the garment, it is clear that one does not put Tzitzis on the garment. Since there is a Safek Mitzvah (Tzitzis), one certainly does not do a Vadai Isur (Sha'atnez) in order to fulfill the Safek Mitzvah. Similarly, even if this person indeed is Chayav Misah, Beis Din may not kill him out of Safek if, by doing so, Beis Din definitely will be doing an act of Retzichah (murder) by killing him. The Safek Mitzvah to put him to death does not override the Isur of killing (when there is no Chiyuv)! (KOVETZ SHI'URIM)
(b) A number of sources prove that a person is not punished when there is a Safek regarding his Chiyuv. That is, besides the logical reason not to punish him (as mentioned in (a) above), when there is a doubt in a monetary matter regarding whether a person is liable or not, Beis Din exempts him. Accordingly, when there is a doubt about whether or not a person is Chayav Misah or Chayav Malkus, Beis Din certainly cannot punish him. Beis Din cannot administer a punishment mi'Safek! Why, then, do Rashi and the Rashbam find it necessary to cite the verse of "v'Hitzilu ha'Edah," which applies only to a Chiyuv Misah, when there is a general rule that Beis Din never acts on a Safek? (TOSFOS DH Safek Nefashos l'Hakel)
The case of the Gemara in Pesachim (12a) is not comparable to the case of the Gemara here with regard to these two questions. The Gemara in Pesachim discusses a situation in which Beis Din has sufficient evidence to kill the defendant. The Gemara there asks why the testimony of the two witnesses provides sufficient evidence; perhaps the witnesses do not mean what Beis Din assumes that they mean. The Gemara there adds that even if there is no reason to suspect that the witnesses do not mean what Beis Din assumes that they mean (because Beis Din does not assume that witnesses are liars if there is no reason for such a suspicion), Beis Din still should not accept their testimony as long as there is a possibility to prove that they are liars, such as by asking them further questions that might cause them to contradict each other. This principle is derived from "v'Hitzilu ha'Edah" which teaches that Beis Din should make every effort, in cases of Dinei Nefashos, to try to acquit the defendant of the death penalty.
(c) If it is true that the person who killed would be Chayav Misah out of doubt, and the only reason he is exempt is because of the verse "v'Hitzilu ha'Edah," then why will a person who commits a Safek Aveirah which is punishable with Malkus be exempt? Many Mishnayos teach that when a person does a Safek Isur d'Oraisa he cannot be punished with Malkus ("Patur Aval Asur"). In those cases, it is not the verse of "v'Hitzilu ha'Edah" which exempts him, because that verse applies only to Dinei Nefashos, cases judged with 23 Dayanim (as that verse teaches). In contrast, a case of a Chiyuv Malkus may be judged with three Dayanim, according to the Chachamim in Sanhedrin (2a), and yet there is no disagreement about the law in the case of a person who does an act of a Safek Chiyuv Malkus -- everyone agrees that such a person is exempt from Malkus, even though the verse of "v'Hitzilu ha'Edah" does not apply. It should be evident, therefore, that there is another factor which exempts a person from Malkus in a case of a Safek, and, likewise, that factor should exempt a person from a Chiyuv Misah in a case of a Safek!
(a) Why is Beis Din able to kill someone when there is no certainty that he is Chayav Misah? Out of doubt, Beis Din should not kill the defendant, lest Beis Din transgress the Isur of Retzichah! The answer is that if Beis Din rules that a person is Chayav Misah, then there is no Isur against killing him. Beis Din has the authority to decide whether a person is Chayav Misah, Chayav Malkus, or not Chayav at all. Beis Din is empowered to make the ruling that a person is Chayav Misah or Chayav Malkus. Once Beis Din makes the ruling, then whether or not the person actually committed the Aveirah, Beis Din has ruled and the person is Chayav. The person can be punished and there is no Isur of Lo Tirtzach (do not kill) or Lo Yosif (do not give Malkus when undeserved), because Beis Din has ruled that the person must be punished. Since the Isur against killing a person does not apply, there is nothing in opposition to the Mitzvah to punish the person. (See AYELES HA'SHACHAR.)
(b) This answer does not explain why Beis Din should rule that a person is Chayav Misah in a case of a Safek. In the case of Dinei Mamonos, as Tosfos says, Beis Din does not rule in the case of a Safek. On the contrary, when Beis Din has a Safek if someone is obligated to pay or not (even in the case of a Kenas), Beis Din does not obligate him to pay. Why, then, in a case of Dinei Nefashos should Beis Din punish the person when there is a Safek?
RAV YOSEF ENGEL (Beis ha'Otzar, Erech Aluf-Yud, #55) and the KOVETZ SHI'URIM suggest an answer that addresses both this question and the previous question. The Rashbam does not mean to say that Beis Din does not kill the master because of "v'Hitzilu ha'Edah." Rather, he means that "v'Hitzilu ha'Edah" teaches that when a person's guilt is in question, the verse exempts him from Misah with certainty. (This is similar to the concept of "Safek Tum'ah b'Reshus ha'Rabim Tahor" and "Safek Tum'ah b'Reshus ha'Yachid Tamei," which teaches that the object of a questionable Tum'ah in Reshus ha'Yachid is Tamei not merely mi'Safek, but it is Vadai Tamei; see Insights to Sotah 28:2.) What difference does it make, though, whether a person is exempt from Misah because of a Safek or because of a Vadai? They explain that one difference would be with regard to the laws of a Shor ha'Niskal. The Mishnah in Sanhedrin (2a) teaches that a Shor that killed is punished with death only in a situation in which, based on such testimony, a person would have been punished with death had the person killed someone. What would be the Halachah in the case of a Shor ha'Niskal that is Chayav Misah out of doubt? If a person is exempt from Misah in such a situation because his Chiyuv is a Safek, then the animal, in such a situation, will be killed mi'Safek, because there is no law of Piku'ach Nefesh that dictates not to kill the animal mi'Safek. If, on the other hand, a person is exempt from Misah out of certainty when his Chiyuv is in doubt, then the Shor ha'Niskal should also be exempt from Misah, just as a person is exempt from Misah.
Why, though, does the Rashbam need to mention this Halachah here? RAV YAKOV KAMINETSKY zt'l (in EMES L'YAKOV) suggests that in the Beraisa, Rebbi Yosi implies that the master who owns an Eved with Kinyan Peros is exempt in all situations, even if he had another Eved which he owned with a Kinyan ha'Guf (and not Kinyan Peros), and he hit both of his Avadim at the same time. Had it not been for the Vadai exemption (learned from the verse of "v'Hitzilu"), he would have been Chayav Misah, because he definitely killed one Eved that was his full Kinyan (even though it is not known which one it is; see Rashi to Yevamos 101a, DH Chayav).
However, Rav Yosef Engel cites five proofs that this is not correct l'Halachah. First, the Gemara in Kerisus (24a) teaches that when a Shor ha'Niskal is Safek Chayav Misah, it is killed. Second, the Gemara in Sanhedrin (36b) teaches that the law of a Shor ha'Niskal is similar to the law of the Chiyuv Misah of a person only with regard to the requirement to be judged by a Beis Din of 23, and not with regard to the Halachos derived from the verse of "v'Hitzilu ha'Edah." Third, the practical difference that Rav Yakov Kaminetzky suggests is not clear because, in that case, the master has a Vadai Chiyuv Misah and not a Safek Chiyuv Misah, and thus "v'Hitzilu ha'Edah" should not exempt him. Fourth, it is not clear why Rashi should mention "v'Hitzilu ha'Edah" in the case of the person who throws a stone into a group of people. Why should Rashi need a Vadai exemption in that case, when the exemption mi'Safek suffices? Finally, if this explanation is correct, then the Rashbam and Rashi need a source for their words that there is a Vadai exemption, and yet there is no such source.
Perhaps an alternative answer may be suggested as follows. In a case of Dinei Mamonos in which Beis Din is not certain whether a person is Chayav, there is no reason to take the money away from one person and give it to another. Why should the other person have more rights than the person who is losing the money? Since Beis Din does not know what to do, Beis Din leaves the money with the person who is holding it. In contrast, in cases of Dinei Nefashos and Dinei Malkus, the punishment also serves as a Kaparah, an atonement, for the person. Perhaps even when Beis Din is not certain whether the person is obligated to receive the punishment, he should receive the punishment out of doubt in order to attain Kaparah. Therefore, Beis Din should rule that he is Chayav so that he may receive the punishment, and thus the atonement, out of doubt. Indeed, such a concept exists in the case of a person who is in doubt about whether he ate Terumah or not. He is obligated to pay a Chomesh to the Kohanim, because the Chomesh is a Kaparah (see Tosfos to Kesuvos 30b, DH Zar). In the case of the Gemara here, Rashi understands that Beis Din may punish a person out of doubt, and it is not like Dinei Mamonos. Although Rashi's source for this is not clear, this approach explains the difference between Dinei Mamonos and Dinei Nefashos.
It should be noted that the doubt is not whether or not the person committed a crime. If there would be a doubt about whether or not he did an Aveirah which obligates him to be punished with Misah, it is clear that Beis Din would not punish him out of doubt, because perhaps he did not sin and he needs no Kaparah. Rather, the master who killed the Eved certainly did an Aveirah of Retzichah (as the Rashbam writes on 50a, DH Mipnei). Similarly, in the Gemara in Kesuvos, when a person threw a stone into a group of people in which there were five Jews and five Nochrim and the stone killed a Jew, the person definitely committed a sin since he knew that his action could result in the death of a Jew (as Tosfos there explains, the Gemara follows the opinion that Hasra'as Safek is a valid Hasra'ah).
(c) Rashi himself seems to have been bothered by the question of why a person is exempt from Malkus in cases of Safek. Rashi writes in numerous places that if a person commits a Safek Aveirah, he is exempt from Malkus because he lacks Hasra'ah, proper warning from witnesses, since his Hasra'ah was a Hasra'as Safek (Yevamos 99b, DH Ein Sofgin; see also Rashi to Yevamos 101a, DH Chayav; Chulin 23b, DH Ela d'Rebbi Yehudah; Chulin 80a, DH Tayish ha'Ba Al ha'Tzeviyah, see Insights there; Chulin 86a, DH she'Eino Sofeg; Sanhedrin 89b, DH Dilma, see ARUCH LA'NER there; Shevuos 37a, DH Hezid, see Insights there). When Rashi uses the term "Hasra'as Safek" in these places, he does not refer to the Machlokes Amora'im in Makos (15b) regarding whether Hasra'as Safek is a valid Hasra'ah. The Gemara in Makos refers to a situation in which it will become clear later whether the Aveirah was transgressed. In contrast, in the case of a Safek Aveirah, it will not become clear later whether or not the Aveirah was transgressed, and thus everyone agrees that the Hasra'ah is lacking, since the transgressor was not warned that what he was doing was a Vadai Aveirah. (In cases of a Safek Aveirah, the transgressor certainly did something wrong, since he knew that he was doing a Safek Aveirah, and therefore he would have been punished had it not been for the fact that it was a Hasra'as Safek, just like the case of the person who threw a stone into a group of people, half of whom were Jews and half were Nochrim.) Rashi's source might be the Gemara in Sanhedrin (89b) which says that when a person eats dates after being warned not to eat them because they might be forbidden (see ME'IRI), he cannot be given Malkus because he did not receive a proper Hasra'ah. The Gemara should have said that he cannot be punished because nobody knows that he sinned. The fact that the Gemara says instead that he is not punished because nobody gave him a proper Hasra'ah implies that one who does a Safek Aveirah does not receive Malkus because his act lacks Hasra'ah.
If Rashi maintains that a person is exempt from Malkus because of Hasra'as Safek, then why does that reason not suffice to exempt a person from Misah as well? A person needs Hasra'ah in order to be Chayav Misah, and thus Rashi should have exempted cases of Safek Nefashos because of the lack of Hasra'ah!
The answer is that in the case of the Gemara here, the person definitely did an Aveirah of Retzichah, for even if he is the true master of the Eved, he is prohibited from killing the Eved. The only question is whether the person is exempted from punishment for his transgression because of the law of "Yom O Yomayim." Therefore, the Hasra'ah that is given to him is a Hasra'as Vadai. Similarly, in the Sugya in Kesuvos there also is a Hasra'as Vadai, because when the stone kills a Jew, it is known for certain that an Aveirah of Retzichah was committed (and the Gemara maintains that a person can be punished for an Aveirah which will become known only after the act is done, as Tosfos there writes). (See also Insights to Kesuvos 15:2.)
2) THE GROUNDS FOR LENIENCY IN A CASE OF "SAFEK NEFASHOS"
QUESTION: The Gemara discusses a case of "Palga u'Palga" in which the perpetrator cannot be punished because of the principle of "Safek Nefashos l'Hakel." RASHI (DH Safek Nefashos) explains that the basis for this principle is the verse, "v'Hitzilu ha'Edah" (Bamidbar 35:25). The RASHBAM (Bava Basra 50b) also cites this verse as the source for ruling leniently in a case of Safek Nefashos.
Although this verse indeed is used to acquit a person suspected of murder in a case in which there is a possible way to vindicate him, the verse should not be necessary to exempt a person from a Chiyuv Misah in the case of a Safek. In the case of a Safek the reason why the person cannot be punished is simply that Beis Din does not know for certain that he is a murderer! This is the reason for leniency in all cases of Safek Nefashos. Even in cases of monetary matters, Beis Din does not make a person pay money when there is a doubt. Certainly Beis Din may not execute a person when there is a doubt in a case of Dinei Nefashos! Why does Rashi not give this simple reason? (TOSFOS to Bava Basra 50b, DH Safek)
(a) RAV ELCHANAN WASSERMAN Hy'd in KOVETZ SHI'URIM (#223) answers that the Rashbam there (and Rashi here) do not mean that the person is exempt mi'Safek, out of doubt, merely because Beis Din is unsure whether he deserves punishment. Rather, he is Vadai Patur -- he is definitely exempt, as if there were no Safek, because the Torah says that in a case of doubt in Dinei Nefashos the person is definitely exempt from Misah. This is what the verse, "v'Hitzilu ha'Edah," teaches. (This is similar to the Torah's Gezeiras ha'Kasuv that a Safek Tum'ah in Reshus ha'Rabim is deemed definitely Tahor.)
Why is it necessary for the Torah to give the person a definite exemption from Misah? Even without a definite exemption from Misah, he would be exempt from Misah because of the general principle that a person cannot be executed out of doubt!
Rav Elchanan Wasserman points out that there are several ramifications of whether he is Patur mi'Safek or Patur b'Vadai. In the case of a Shor ha'Niskal, an ox that must be put to death because it killed a person, the rule (based on a Hekesh) is that the ox is put to death only in a situation in which a person would have been put to death had he committed the same act. In a case where there is a Safek whether the Shor needs to be killed, does Beis Din kill it or not? If a person, in a case of a Safek Dinei Nefashos, is exempt from Misah only because Beis Din cannot administer the Chiyuv Misah out of doubt, then Beis Din could kill the Shor out of doubt because -- in contrast to executing an innocent person -- there is no prohibition of murder involved in killing an innocent Shor if the Shor is not deserving of death. If, however, the Torah teaches that a person is exempt b'Vadai in a case of Safek Nefashos, the Shor should also be exempt because of the Hekesh.
Another difference between whether a person is Patur mi'Safek or Patur b'Vadai is whether the principle of "Kam Lei bid'Rabah Minei" applies in a case of Safek. The principle of "Kam Lei" states that when a person becomes liable for two punishments (such as Misah and a monetary payment) at one time, he receives only the larger, more severe punishment. What is the law in the case of a person who becomes Chayav to pay money at the same time that he becomes Safek Chayav Misah? If his exemption from Misah is only because of a Safek, he remains exempt from paying money because Beis Din cannot make him pay out of doubt (because perhaps in truth he really is Chayav Misah, which would exempt him from the payment, and thus the person to whom he owes the money must bring proof that the alleged perpetrator is definitely exempt from Misah). A Safek Chiyuv Misah is enough to exempt him from payment. If, however, he is definitely exempt from Misah, then he should have to pay the money because there is no punishment of Misah, not even mi'Safek, to exempt him.
Perhaps Rashi finds it necessary to mention the verse, "v'Hitzilu ha'Edah," because of the question of Tosfos. Tosfos (DH v'Safek) asks that according to the opinion that "Hasra'as Safek Shmah Hasra'ah" -- a Hasra'ah given to a person who is about to do is a Safek Aveirah is considered a valid Hasra'ah (to make him liable for punishment) -- the person should be Chayav in this case (since it is clear that a Jew was killed, even though the perpetrator was in doubt about who would be killed at the time that he threw the rock).
Rashi may intend to answer this question when he says that since there is a definite exemption of "v'Hitzilu ha'Edah," the Hasra'ah here is not considered a Hasra'ah at all since no Aveirah was done, even according to the opinion that Hasra'as Safek normally is a valid Hasra'ah.
(b) This approach, however, is problematic. First, this approach does not explain why the Rashbam in Bava Basra needs to mention the verse of "v'Hitzilu ha'Edah" in that Sugya. There, it would suffice to say that Beis Din may not punish a person with Misah out of doubt.
Second, in the case of Shor ha'Niskal, why would Beis Din kill the Shor out of Safek? The owner of the Shor has a Chezkas Mamon which should dictate that the Shor not be killed out of doubt, and since it is not killed the owner should be permitted to derive benefit from it. Moreover, even if a man's exemption from Misah is mi'Safek, there is still reason to say that the Hekesh exempts the Shor from Misah in a similar case of Safek, because the Hekesh says that whenever a person is exempt a Shor is also exempt!
Third, the case of "Kam Lei" also should not be affected by whether the person is exempt mi'Safek or whether he is exempt b'Vadai. According to those who say that one who killed inadvertently (and is thus not Chayav Misah) is nevertheless exempt from monetary payments because of "Kam Lei," why is the Gemara's case of a Safek Chiyuv Misah different from a case of one who killed inadvertently? This case also should be treated like a Safek; although he definitely is exempt from Misah, the very fact that he killed should exempt him from paying!
According to the opinion that one who killed inadvertently is not exempt from paying (because that opinion maintains that "Kam Lei" does not apply when the Aveirah was done b'Shogeg), it is obvious that he should be Chayav to pay even if the exemption from Misah is only mi'Safek because "Kam Lei" exempts a person from paying only when Beis Din applies a punishment of Misah; it does not exempt him from payment if the Chiyuv Misah cannot be applied in practice.
In the case of the Gemara here, the verse of "v'Hitzilu ha'Edah" cannot be applied to exempt a person from Misah according to the opinion that Hasra'as Safek is a valid Hasra'ah. "V'Hitzilu ha'Edah" is only an exemption from punishment when Beis Din is unsure that the person killed someone; it does not make the Aveirah of throwing a rock into a crowd of people any less of an Aveirah if it turns out that it caused someone's death. The Aveirah is the same Aveirah; the perpetrator is just exempt from punishment. Since, in this case, Beis Din knows that his act eventually killed someone, "v'Hitzilu ha'Edah" cannot exempt him from Misah because the Hasra'ah was a valid Hasra'ah according to the opinion that Hasra'as Safek is a valid Hasra'ah.
Rashi in other places makes similar statements concerning the reason why a person is exempt in a case of Safek. Rashi in Yevamos (99b, DH Ein Sofgin) writes that if a Safek Kohen becomes Tamei for a Mes, he does not receive Malkus because the Hasra'ah was a Hasra'as Safek. Why does Rashi there not say that the reason the person is exempt from Malkus is because Beis Din cannot punish a person when it is not known for certain that he committed a sin?
Rashi makes the same statement about Chiyuv Malkus in a number of places in Chulin (23b, end of DH Ela d'Rebbi Yehudah; 80a, DH Hasra'as Safek; 86b, DH she'Eino Sofeg).
Apparently, Rashi understands that the principle of "Safek d'Oraisa l'Chumra" (in a case of doubt regarding a Torah law, one must act stringently) is a rule d'Oraisa, as many other Rishonim explain (see Rashba to Chulin 9b, and Shev Shemaitsa 1:1). (This is in contrast to the view of the Rambam, who maintains that "Safek d'Oraisa l'Chumra" is d'Rabanan. See Insights to Kidushin 73:1, Bava Metzia 7:1, and Chulin 11:3.) In a case of a Safek in a monetary case the law does not require that the person pay mi'Safek, because it is not known for certain that he owes money. The same law should apply in a case of Dinei Nefashos when it is not known for certain that the person killed (for example, there is a doubt about whether this person killed or another person killed). The person is exempt from Misah because Beis Din does not know for certain that he is guilty. However, when the person committed an act which he knew was an act of a Safek Aveirah, perhaps he is considered to have committed a definite Aveirah; the law that a Safek Aveirah mid'Oraisa is forbidden mid'Oraisa may mean that it has the same status as a definite Aveirah. The Mitzvah in the Torah which tells him not to do an Aveirah when it is Vadai is the same Mitzvah that tells him not to do an Aveirah when it is a Safek. Consequently, he should be punished for the Safek Aveirah that he committed (even though it was a Safek at the time he did the act), since he committed an act which he knew was prohibited by the Torah. This is why Rashi writes that in the case of Malkus, the person is exempt from punishment because of Hasra'as Safek, while in the case of Safek Nefashos (the case of the Gemara here) he is exempt because of the verse, "v'Hitzilu ha'Edah."
One question is left unanswered. Why does Rashi here need to write the new reason of "v'Hitzilu ha'Edah" and it does not suffice to say that the exemption is because of Hasra'as Safek? The answer cannot be that there is an opinion that says Hasra'as Safek is not a Hasra'ah, because this type of Hasra'as Safek is not a Hasra'ah according to everyone (even according to Reish Lakish, who says that a normal case of Hasra'as Safek is a valid Hasra'ah). Why, then, does Rashi give a new reason ("v'Hitzilu") and not the reason of Hasra'as Safek?
It seems that Rashi infers from the wording of the Gemara, "Safek Nefashos l'Hakel," that the exemption here is a specific exemption in the laws of Dinei Nefashos (and does not apply elsewhere, such as to exempt a person in a case of Malkus). Why, though, does the Gemara itself give a new reason to exempt a person from Misah in the case of a Safek Aveirah? Why does the normal reason of Hasra'as Safek, which exempts a person in a case of Malkus, not suffice to exempt him here as well?
Apparently, the reason of Hasra'as Safek cannot exempt a person from Misah because there is a difference in the nature of the Hasra'os for Misah and for Malkus. Rashi in Shevuos (20b, DH v'Azharasei) writes that the witness who gives the Hasra'ah must mention the verse in the Torah which the sinner is about to transgress. When the witness gives Hasra'ah for Misah, does he also need to mention the prohibition in the Torah which prohibits the act that the person is about to commit? The Gemara in Sanhedrin (8b) says that he must mention only what the punishment for the act is; it does not say that he must mention the specific verse in the Torah which prohibits the act. It could be that in a case of an Aveirah punishable with Misah, the purpose of the Hasra'ah is only to relate what the punishment is, but not to relate the verse that describes the prohibition. The only reason why the witness must mention the prohibition when he gives Hasra'ah for Malkus is that he needs to show where the punishment of Malkus is written in the Torah for the act that the sinner is about to commit. (The Malkus for every Lo Ta'aseh is derived from "Lo Sachsom." By mentioning the verse of the Lo Ta'aseh that the person is about to commit, one thereby shows that its Malkus is derived from the Lo Ta'aseh of "Lo Sachsom.") Since he must mention the verse of the prohibition in the case of a Lo Ta'aseh, and the Aveirah that the person is doing is only a Safek, the verse (which prohibits a Vadai Aveirah) that he mentions for the Hasra'ah does not refer to the act that the sinner is doing (which is a Safek Aveirah). Hence, it is a Hasra'as Safek and the sinner cannot be punished for it. In contrast, when one gives Hasra'ah for a Chiyuv Misah, in which he does not mention the prohibition in the Torah but only the punishment, it is not a Hasra'as Safek because he will certainly get the punishment if he commits the Aveirah! That is why a separate exemption of "v'Hitzilu ha'Edah" is needed.