Emor - Rishon
With Great Power Comes Great Responsibility
G-d gave Moshe instructions for the kohanim (priests). They were not permitted to become unclean through proximity to a corpse, except for one of the seven close relatives (father, mother, sister, brother, son, daughter, wife). Even then, there are restrictions: his sister must be unmarried and his wife must be someone permitted to him. (Be patient; we'll get there in a second.) Since they perform G-d's service, they must be especially careful not to tear their hair out or injure themselves in their grief. A kohein may not marry a divorcee or a woman who is the product of a disqualifying union. A woman who has had relations with a person forbidden to her is also unable to marry a kohein.
If a kohein's married daughter commits adultery, the penalty is burning, rather than strangulation. The harsher form of execution is because of her elevated status.
There are extra rules for the anointed High Priest: he can't go without a haircut more than a week (as opposed to other kohanim, who got their hair cut every 30 days - see Talmud Sanhedrin 22b). He could not expose himself to corpse uncleanliness, even for a close relative. Unlike regular kohanim, the Kohein Gadol couldn't marry a widow; he had to marry a virgin (and he HAD to be married).