The GNSO Council requested an Issue Report on 'thick' WHOIS at its meeting on 22 September 2011 noting that the Issue Report should 'not only consider a possible requirement of 'thick' WHOIS for all incumbent gTLDs in the context of IRTP, but should also consider any other positive and/or negative effects that are likely to occur outside of IRTP that would need to be taken into account when deciding whether a requirement of 'thick' WHOIS for all incumbent gTLDs would be desirable or not'.
Final Report on the Thick WHOIS Policy Development Process [PDF, 1.23 MB] was released on October 2013 as a required step in this GNSO Policy Development Process on thick WHOIS.
For the generic top-level domain (gTLD) registries, ICANN specifies WHOIS service requirements through the registry agreements (Registry Agreements [PDF, 2.1 MB]) and the Registrar Accreditation Agreement (RAA). Registries satisfy their WHOIS obligations using different services.
The two common models are often characterized as "thin" and "thick" WHOIS registries. This distinction is based on how two distinct sets of data are managed. One set of data is associated with the domain name, and a second set of data is associated with the registrant of the domain name. A thin registry only stores and manages the information associated with the domain name. This data set includes data sufficient to identify the sponsoring registrar, status of the registration, creation and expiration dates for each registration, name server data, the last time the record was updated in its WHOIS data store, and the URL for the registrar's WHOIS service. With thin registries, Registrars manage the second set of data associated with the registrant of the domain and provide it via their own WHOIS services, as required by Section 3.3 of the RAA 3.3 for those domains they sponsor. Thick WHOIS output by contrast includes a broader set of data elements including contact information for the registrant and designated administrative and technical contacts.
It is important to note that, regardless of the thin or thick nature of registry WHOIS output for any registration, the sponsoring registrar is always required to display a "thick" set of contact data for all registrations it sponsors.
While current registry agreements have differing provisions with regards to the WHOIS output specification, ICANN's intent with the next round of new gTLDs has been to have the agreements as standard as possible, with minimal or no individual negotiation and variation of provisions such as a registry's WHOIS output specification.
Within the context of the new gTLD program, new gTLD registries will be required to operate a 'thick' WHOIS model.
This recommendation was adopted by the GNSO Council at its meeting on 22 September 2011 (see http://gnso.icann.org/resolutions/).
The GNSO Council launched a Policy Development Process (PDP) on the use of 'thick' WHOIS by all gTLD Registries, both existing and future on 14 March 2012 (see PDP WG Charter, set forth at https://community.icann.org/x/vIg3Ag).
The Final Report on the Thick WHOIS Policy Development Process [PDF, 1.23 MB] delivered on 21 October 2013.
The GNSO Council reviewed and discussed the recommendations of the Thick WHOIS PDP WG, and adopted the Recommendations on 31 October 2013 by a Supermajority and unanimous vote (see http://gnso.icann.org/en/council/resolutions#20131031-1).
The ICANN Board on 7 Feb 2014 adopted the GNSO Council Policy Recommendations for a new Consensus Policy on Thick WHOIS as set forth in section 7.1 of the Final Report (see http://gnso.icann.org/en/issues/WHOIS/thick-final-21oct13-en.pdf [PDF, 1.23 MB]).
The Board Resolutions are 2014.02.07.08 - 2014.02.07.09 https://www.icann.org/resources/board-material/resolutions-2014-02-07-en#2.c