In this week’s parshah we learn about the garments of the kohanim. Interestingly, several of the garments were comprised of wool and linen, i.e., shaatnez. Generally, one may not wear a garment with shaatnez, but the Torah makes an exception for the kohanim’s garments.
There is a machlokes between the Rambam and the Raavad whether a kohen may wear his garments when he is not performing the avodah. The Rambam (Hilchos Kilaim 10:32) writes that kohanim may only wear their garments during the avodah, which is a mitzvah. If they wear them any other time they receive lashes for transgressing the prohibition of shaatnez. The Raavad disagrees and argues that kohanim may always wear their special garments.
The Chasam Sofer (teshuvos Yoreh Deah 69) questions the Rambam’s view. We know (Gittin 54b) that the avodah is invalid if the kohen harbors wrong thoughts while performing it and must compensate the owner of the korban for the loss of his animal. According to the Rambam, though, he shouldn’t have to pay anything. Since he harbored wrong thoughts, it turns out that he wasn’t really performing the avodah. And if he wasn’t really performing the avodah, it emerges that he was wearing shaatnez garments illegally. Now, we know that anyone who transgresses a prohibition punishable by lashes while also incurring a monetary debt at the same time need not pay the debt. This rule is known as “ein lokin u’meshalem” – one need not be flogged and pay money. Rather, one only receives lashes. Thus, according to the Rambam, this kohen should be flogged but he shouldn’t have to compensate the owner for his korban. And yet the Gemara says that he must!
The Chasam Sofer suggests that the Rambam maintains that this kohen is not in violation of wearing shaatnez even though he wasn’t performing the avodah (due to his wrong thoughts). Why not? Because one only transgresses this prohibition if one wears a shaatnez garment for pleasure (which is why clothing merchants are permitted to wear shaatnez garments they are selling). Since the kohen is clearly only wearing his garments for the sake of performing the avodah, he isn’t in violation of wearing shaatnez even if it emerges that his avodah was invalid and thus not performing the avodah after all.
Many acharonim are dissatisfied with the Chasam Sofer’s answer. They point to several places where it is evident that a kohen can in theory violate the aveirah of shaatnez while wearing his garments for the avodah. The Gemara (Menachos 43a and Eruchin 3b) says that since the Torah permitted a kohen to wear shaatnez, his garments do not require tzitzis. This statement implies that if not for a special heter from the Torah, there would be a problem of shaatnez. According to the Chasam Sofer’s reasoning, however, there is no need for a special heter; there is no issue of shaatnez to begin with.
Additionally the Rambam (Hilchos Kilaim 10:32) writes that kohanim may only wear their garments because they are performing a mitzvah. This statement implies that, but for the mitzvah, they would be in violation of the aveirah of shaatnez by wearing these garments.
I would suggest the following: The Chasam Sofer’s principle is correct. A person only transgresses the prohibition of shaatnez when he has pleasure from the garments, and a kohen doing the avodah is not wearing his garments for pleasure; rather he is wearing them as his uniform. However, the Torah’s command for the kohen to wear them l’kavod u’litiferres means that the kohanim will regard wearing their garments as a meaningful and pleasing experience. The mitzvah itself creates a situation whereby one can violate the aveirah of shaatnez.
However this principle only applies while the kohen is actually performing the avodah. If he is not truly performing the avodah – due to him having wrong thoughts – his wearing of the garments becomes “ordinary” and the shaatnez problem disappears.