Two other types of liability, contractual and relational, must receive brief notice. The former has long done valiant service for the will theory. Not only liability arising from legal transactions but liability attached to an office or calling, liability attached to relations and liability to restitution in case of unjust enrichment have been referred to express or implied undertaking and hence to the will of the person held.
[See the full post at: Liability-ROSCOE POUND]