A legal contractor is someone, usually a member of Pandora, who makes a contract with a chain using a Carcere. This method was originally devised by Pandora and provides a much safer alternative to illegally contracting with chains. It does however have some side affects such as causing certain contractors like Xerxes Break and Sharon Rainsworth to stop physically aging. It also limits the amount of power that contractors and chains can use.
Unlike Illegal Contractors, Legal Contractors don't have clock-like seals on their chests and they don't have to worry about how much time their contract has left. Instead of consuming a chain's blood to form a contract, legal contractors use the blood seal mirror to absorb the chain's blood, and thus their seals are stored inside the mirror itself. Most of the legal contractors are part of Pandora.