"The concept of legal "ownership" of IP addresses as property is explicitly denied by ARIN and RIPE NCC policy documents and by the ARIN Registration Services Agreement. It is not even clear in which country's legal system the lawsuits would be resolved."
http://en.wikipedia.org/wiki/IPv4_address_exhaustion#Markets...
"The concept of legal "ownership" of IP addresses as property is explicitly denied by ARIN and RIPE NCC policy documents and by the ARIN Registration Services Agreement. It is not even clear in which country's legal system the lawsuits would be resolved."