1,308. For Whom May a Kohein Become Impure?

202:10 Some authorities say that a non-Jewish corpse also imparts ritual impurity under a canopy. One must take appropriate precautions according to this position and not walk on a non-Jew's grave. This is all the more the case if there is reason to suspect that an apostate Jew may be buried there since an apostate is still considered a Jew. The offspring of a female apostate with a non-Jewish man is likewise considered a Jew.

202:11 A kohein is permitted to expose himself to ritual impurity for his closest relatives; in fact, it is a mitzvah for him to do so. These are the relatives for whom this applies: his wife - assuming that she is a woman whom the kohein is allowed to marry - his father, his mother, his son, his daughter, and his brother and sister who share the same father, as long as they lived thirty days; a kohein may not become impure for an infant suspected of not being viable. He also does not become impure for a married sister.

Some authorities say a kohein's permission and obligation to become impure for a relative only apply to the needs of the funeral or for the bringing the deceased a coffin, shrouds, etc. Therefore, on Shabbos, when it's not possible to bury the deceased on that day, the kohein is not allowed to render himself impure, not even to watch the body. It's appropriate for one to act stringently in this matter. However, when it comes to funeral needs, it's certainly a mitzvah to become impure for them. Even if there is a chevra kadisha (burial society) available to take care of the preparations so that the kohein doesn't need to do anything, he's nevertheless permitted to remain in the house, in case they need something. A kohein may only render himself impure for these relatives until the time when the grave is closed, but not after that.