http://www.securityweek.com/eff-warns-police-courts-about-unreliability-ip-addresses

The article states that the Electronic Frontier Foundatoin has published a report warning of the misuse of IP addresses by police and courts.  Recently, there have been an increasing amount of reports that law enforcement often consider IP addresses to be a clear indicator of a person's location or identity.  However, this is not always the case.  One of the main issues is that police often overstate the reliability of IP address information when trying to obtain a warrant of subpoena.  According to the EFF, law enforcement often times use inaccurate metaphors to explain IP addresses like comparing them to a physical mailing address or a license plate.  The EFF has advised police to treat IP information the same way as police would treat a tip from an anonymous informant. The EFF has also listed some other recommendations for law enforcement to use IP addressing information more efficiently to help protect innocent people.