Do the schools of law differ on whether a girl may marry herself off without a guardian?

A woman is not permitted to marry herself off except with the permission of her guardian (wali), whether she is a virgin or previously married. This is based on the Prophet's (peace and blessings be upon him) sayings: "There is no marriage except with a guardian" and "Any woman who marries without the permission of her guardian, her marriage is invalid." Although Abu Hanifa held the view that a previously married woman and a mature virgin may marry without the guardian's permission, the opinion of the majority is the more authoritative.