Leviticus and the Law Codes in the Pentateuch

According to leviticus 17, eating dead animals is a cause of uncleanness. In 22, however, chapter 22, priests are specifically prohibited from eating carcasses at all. If they do, they will i in the sanctuary. For h, priests operate on a higher level, let's say, than joe and jane israelite. Now compare this to deuteronomy chapter 14. There we read yet a third perspective, that no one shall eat anything that dies on its own.