FBI, Drug Enforcement Administration, and Royal Canadian Mounted Police officials have told industry representatives that IPv6 traceability is necessary to identify people suspected of crimes. The FBI has even suggested that a new law may be necessary if the private sector doesn't do enough voluntarily.

ARIN and the other regional registries maintain public Whois databases for IP addresses, meaning that if you type in 64.30.224.118, you can see that it's registered to CNET's publisher. ARIN tries to ensure that Internet providers keep their segments of the Whois database updated, and because it's been handing out IPv4 addresses blocks every few months, it currently enjoys enough leverage to insist on it.

But for IPv6, ARIN will be handing out much larger Internet address blocks only every 10 to 15 years, meaning it loses much of its ability to convince Internet providers to keep their Whois entries up-to-date. That means it may take law enforcement agencies -- presumably armed with court orders -- longer to trace an IPv6 address such as 2001:4860:4860::8888 back to an Internet service provider's customer.