Kohanim are prohibited to become ritually impure through contact with the dead, as the verse states: “Speak to the priests, the sons of Aaron, and say to them: He shall not become impure from a dead person among his people” (Leviticus 21:1). The practical application of this prohibition is that a kohen may not touch a corpse, nor be under the same roof with a corpse. This last category also applies to an awning or a tree that extends over a dead body; a kohen may not stand anywhere under them. This law imposes various limitations on a kohen who wishes to attend a funeral.

Kohanim may not come within four cubits, approximately two meters, of a corpse or a grave. However, if a first-degree family member of a kohen passes away – a group that includes his father, mother, son, daughter, wife, brother, and unmarried sister from a common father – he is permitted to become ritually impure through proximity to the body at the funeral, and it is in fact a mitzva to do so. At the same time, he is prohibited – even during their funeral and burial – to become impure through contact with any other corpses or to approach their graves. For this reason, when the deceased is a kohen or if many of his family members are kohanim, the hevra kadisha will attempt to provide a burial plot in an outer row of graves, which can be accessed without passing in immediate proximity to other graves.

There are other limitations that apply to kohanim as a result of the prohibition for them to have contact, be under the same roof, or in immediate proximity to a corpse:

Cemeteries

Kohanim should refrain as much as possible from visiting cemeteries. If they do visit one, they must be careful not to enter within four cubits (about two meters) of any grave, as stated above. They are also prohibited to enter a funeral home while a body is present there. Many funeral homes have a separate area for kohanim, which allows them to attend the funeral and hear the eulogies without being situated under the same roof as the deceased.

Medical centers

The entrance of kohanim into a hospital where there are likely to be corpses present at any given time also presents halakhic difficulties. There are medical centers in Israel which provide a warning to kohanim when there is a dead body on the premises. At such a time kohanim know for certain that they may not be there. When there is a special need for a kohen to enter a medical facility in order to visit a friend or relative, or if he himself requires medical attention, he should first consult with a rabbi. Of course, in life-threatening situations, these restrictions do not apply.

Medical studies

Medical studies present a halakhic problem for a kohen, as this field requires contact with cadavers and the examination of tissue taken from dead people, which also impart ritual impurity. A kohen who wishes to study medicine should consult a rabbi.