Is it possible today for a Cohen to study medicine, taking into considerstion the various prohibitions regarding Cohanim?
It was the considered opinion of my great Rebbe, HaRav Joseph B. Soloveitchik Zt"l, that no Cohen would be permitted to study medicine today for the medical training today demands involvement in pathology,which would render to Cohen "Tomei" (which a Biblical prohibition). As early as the HaRav David Zvi Hoffman, of the Hillesheimer Rabbinic Seminary in Berlin (some 80 years ago), penalized Cohanim who studied medicine, by not allowing them to participate in Birkat Cohanim, and were not called to the Torah for the first Aliyah. As Rav Soloveitchik pointed out, there's no "Pikuach Nefesh" at stake, for so many are just waiting on line for admission to medical school. If Mr. Cohen doesn't go, someone else certainly will! While the normative opinion is in conformity with Rambam's view that Cohanim must certainly abide today by the rules of spiritual purity, there is a view mentioned by the Ravad (R' Abraham b. David of Posquiere), that no judicial punitive measure could be taken today against a Cohen in blatant violation of these laws, for the onus of proving who is a contemporary Cohen falls upon the accusor and not the Cohen himself. This has led some to opine that Ravad rules leniently on this issue, and, hence, a Cohen could actually study medicine today. However, the overwhelming sentiment of Halachic thinking runs contrary to this assumption. Having said all this, I am personally acquainted with a wonderful medical person who is a Cohen, and claims to have "avoided" Tumah contamination throughout his schooling with the blessings of some Posek. He practices in a medical area that does not require any hospital visitations. I think that there's still a "Mar'it Ayin" question in this particular case.