Law Library of Congress Implements Solution for Link and Reference Rot

Apr 13, 2016

Last fall, the Law Library of Congress implemented an external archiving solution for the problem of link and reference rot in its legal research reports. “Link rot” and “reference rot” (a.k.a. “content drift”) are the terms used to describe, respectively, the problem of non-working Web addresses and Web addresses that work but link to modified content different from what the user originally saw. Link rot is most commonly identified when a user receives the familiar “404—File Not Found” error message, or a similar error message, on his or her computer screen. Reference rot can be more difficult to spot without text comparison software, but may be indicated by a “last modified” message at the bottom of a Web page. Both problems are the byproduct of Internet impermanence—websites can be redesigned or shut down, content can be moved or changed, or service can be restricted without advance notice.

Exterior architecture details of the James Madison Building, where the Law Library is located, at the Library of Congress

During a 2014 internal quality assurance review of foreign, comparative and international law reports prepared by the Law Library’s Global Legal Research Center and published under the Legal Reports section of, Law Library staff found that a significant number of linked references in the report footnotes no longer worked. Their discovery was not unique: studies by other entities have found that a surprising number of Web addresses in law journal and court opinion footnotes fail to work or take the reader to content different from what the author intended, which is especially problematic in the legal world where research documentation and reliable access to historic precedents are paramount. A study that appeared in the March 2014 edition of the Harvard Law Review Forum found, for example, that 33-40% of Web addresses in the footnotes of three Harvard law journals and 36% of Web addresses in U.S. Supreme Court decisions from 1996 to 2012 suffered from link rot, and reference rot figures were even higher. Similar results have been documented by the scientific community.

The Law Library’s discovery regarding the extent of link rot in its own reports led to the search for an archiving solution that would allow readers of those reports to access linked content in real time, as they were reading, without having to jump out of the report to search a database of archived material. The exploration of options ultimately lead to a solution known as, developed specifically for the legal community by the Harvard Library Innovation Lab. allows authors to archive documents referenced in their work as they are writing and simultaneously generates a permalink to the archived document for inclusion in the work.

A metal chain with a rotting, rusted section of links.

After negotiating an addendum to’s terms of service to allow for federal entity participation and providing extensive staff training, was officially implemented by the Law Library on October 1, 2015. This means that hyperlinked footnote references in new Global Legal Research Center reports—such as the Center’s recent reports on foreign fighters, human trafficking or national parliaments—now contain links to archived versions of referenced Web pages, allowing readers permanent access to key legal materials, regardless of what happens to the original Web address.

  • 404/File Not Found: Link Rot, Legal Citation and Projects to Preserve Precedent, Georgetown University Law Library Symposium (Oct. 24, 2014) (collection of conference materials).
  • Jonathan Zittrain et al., Perma: Scoping and Addressing the Problem of Link and Reference Rot in Legal Citations, 127 Harvard Law Review Forum 165, 174 (2014).
  • Nicholas Szydlowski, A Dead Link or a Final Resting Place: Link Rot in Legal Citations, 18 AALL Spectrum 7 (Apr. 2014).
  • Martin Klein et al., Scholarly Context Not Found: One in Five Articles Suffers from Reference Rot, Public Library Sciences Journal (Dec. 26, 2014) (focusing on the extent of the problem in science, technology, and medicine articles).
  • The Hiberlink Project, an international collaboration between the University of Edinburgh and the Los Alamos National Laboratory, is studying the extent of link and reference rot and developing solutions. The Hiberlink website provides regular updates on the project and links to partner sites.
  • Leighton Walter Kille, The Growing Problem of Internet “Link Rot” and Best Practices for Media and Online Publishers, Journalist’s Resource (July 15, 2015).Charlotte Stichter is Managing Editor of the Law Library of Congress. The opinions expressed in this article are her own and do not necessarily reflect the views of the Law Library or the Library of Congress. Questions or comments about this article may be sent to Ms. Stichter via email.
Originally posted by Charlotte Stichter on Apr 13, 2016
Apr 13, 2016