Sefer Ha’mitzvos Ha’Katzar (The concise book of mitzvos) By the Chofetz Chaim

This book lists the Torah mitzvos that can be observed today

Second Section – the Negative Commandments

141. It is a negative commandment “a Cohain shall not become ritually impure from a dead body.”

As it states in Vayikra (Leviticus) 21:1, “He shall not make himself ritually impure among his people for a dead person.” This includes touching a dead body, going above it, carrying it, or touching his grave. The same law applies to coming in contact with the dead body as coming in contact with one of the ritual impurities which flows from his body, like blood. If the Cohain made himself ritually impure knowingly, then he is given lashes. For a body which it is a commandment to bury [a body which no one is taking care of its burial], it is allowable for the Cohain to make himself ritually impure for this body.

This applies in all places and at all times, for men that are fit to be a Cohain, but not an unfit Cohain or women.