An HTTP Status Code to Report Legal Obstacles
RFC 7725

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Internet Engineering Task Force (IETF)                           T. Bray
Request for Comments: 7725                                    Textuality
Category: Standards Track                                  February 2016
ISSN: 2070-1721

             An HTTP Status Code to Report Legal Obstacles

Abstract

   This document specifies a Hypertext Transfer Protocol (HTTP) status
   code for use when resource access is denied as a consequence of legal
   demands.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7725.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Bray                         Standards Track                    [Page 1]
RFC 7725                     HTTP-status-451               February 2016

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  451 Unavailable For Legal Reasons . . . . . . . . . . . . . .   2
   4.  Identifying Blocking Entities . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   This document specifies a Hypertext Transfer Protocol (HTTP) status
   code for use when a server operator has received a legal demand to
   deny access to a resource or to a set of resources that includes the
   requested resource.

   This status code can be used to provide transparency in circumstances
   where issues of law or public policy affect server operations.  This
   transparency may be beneficial both to these operators and to end
   users.

   [RFC4924] discusses the forces working against transparent operation
   of the Internet; these clearly include legal interventions to
   restrict access to content.  As that document notes, and as Section 4
   of [RFC4084] states, such restrictions should be made explicit.

2.  Requirements

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  451 Unavailable For Legal Reasons

   This status code indicates that the server is denying access to the
   resource as a consequence of a legal demand.

   The server in question might not be an origin server.  This type of
   legal demand typically most directly affects the operations of ISPs
   and search engines.

   Responses using this status code SHOULD include an explanation, in
   the response body, of the details of the legal demand: the party
   making it, the applicable legislation or regulation, and what classes
   of person and resource it applies to.  For example:

Bray                         Standards Track                    [Page 2]
RFC 7725                     HTTP-status-451               February 2016

   HTTP/1.1 451 Unavailable For Legal Reasons
   Link: <https://spqr.example.org/legislatione>; rel="blocked-by"
   Content-Type: text/html

   <html>
    <head><title>Unavailable For Legal Reasons</title></head>
    <body>
     <h1>Unavailable For Legal Reasons</h1>
     <p>This request may not be serviced in the Roman Province
     of Judea due to the Lex Julia Majestatis, which disallows
     access to resources hosted on servers deemed to be
     operated by the People's Front of Judea.</p>
    </body>
   </html>

   The use of the 451 status code implies neither the existence nor
   nonexistence of the resource named in the request.  That is to say,
   it is possible that if the legal demands were removed, a request for