It is forbidden for Kohanim to contract Tum’at Met – the status of impurity that results from contact with a human corpse. The Halachic authorities addressed the question of whether it would be permissible for a Kohen to volunteer for an emergency medical corps, such as Hatzalah. A person working as an emergency medical responder is likely to come in contact with a human corpse, Heaven forbid. In light of this likelihood, is it forbidden for a Kohen to volunteer for such services?
The Shebet Halevi (Rav Shemuel Wosner, contemporary) rules that a Kohen may volunteer for Hatzalah, as long as he exercises caution and tries to avoid contact with a human corpse. If he tries to avoid Tum’at Met, then it is permissible to join emergency ambulance services, and it would in fact be considered a Misva for him to do so. Of course, in situations where a Kohen’s involvement could save a life, then he is certainly allowed and required to intervene, even if this poses the risk of becoming Tameh. Just as one may violate Shabbat and eat and Yom Kippur when this is necessary for Piku’ah Nefesh (saving a life), similarly, a Kohen may come in contact with Tum’at Met for the purpose of saving a life.
The Hatam Sofer (Rabbi Moshe Sofer of Pressburg, 1762-1839) addressed the situation of a Jew who had passed away, and the coroner insisted on determining the precise cause of death. If the cause of death could not be definitively determined through an external inspection, then the coroner would order an autopsy. As it turned out, the only available physician who was capable of determining the cause of death was a Kohen. The Hatam Sofer ruled that the Kohen was allowed to – and in fact should – inspect the body in order to prevent the autopsy. This situation, the Hatam Sofer explained, was no different than that of a "Met Misva," where a Kohen is the only person available to bury a body, in which case he is allowed, and even required, to perform the burial. Here, too, the Kohen is needed to ensure the body’s immediate burial and avoid disgrace, and therefore he should inspect the body, even though he would then become Tameh.
These Halachot should remind us of the need for Kohanim to consult with Rabbis on all matters involving situations of possible contact with a corpse, to determine when it is forbidden, permissible, or even obligatory to come in contact with a corpse.
Summary: It is permissible – and even a Misva – for a Kohen to serve on an emergency ambulance corps, provided that he exercise care to try and avoid contact with human corpses. If a body needs to be inspected to determine cause of death and thereby avoid an autopsy, and the only available doctor to perform the inspection is a Kohen, he is allowed and even urged to inspect the body, even though he would thus become Tameh.