National Pulse

'Link rot’ is degrading legal research and case cites

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Illustration by Viktor Koen

The World Wide Web may seem like a limitless superhighway. But it is filled with dead ends: hyperlinks that point to webpages that have become permanently unavailable. It’s a phenomenon known as “link rot.”

While landing on a broken link can be frustrating, a growing body of research has identified more dire implications. A subcategory—“reference rot”—occurs when the link exists, but the information referenced is no longer present. With the continued growth of the Internet, the amount of such rot has been accelerating, studies have shown, imperiling citation references in academic research and case law. For practicing lawyers, link rot is making it harder to find examples of legal precedent.

“We cannot predict which links will or will not rot,” says Raizel Liebler, head of faculty scholarship initiatives at the John Marshall Law School in Chicago. Government links, private links and those on educational sites rot, “and we can’t predict which links will remain accessible.”

Liebler and John Marshall’s chief information officer, June Liebert, co-authored “Something Rotten in the State of Legal Citation: The Life Span of a United States Supreme Court Citation Containing an Internet Link (1996-2010).” The study (PDF), published this summer in the Yale Journal of Law and Technology, found that nearly one-third of the websites cited by the U.S. Supreme Court were nonfunctioning, many of which linked to government or education domains.


“Is link rot destroying stare decisis as we know it?” asked Minnesota’s former chief justice, Eric Magnuson, at an August panel on the digital future of 21st century courts. “It is scary, scary stuff.”

In a similar study building on Liebler and Liebert’s work, Harvard law professor Jonathan Zittrain reports the percentage of defunct links to be at 50 percent. Zittrain’s study, conducted with law student Kendra Albert, also found that 70 percent of the links in the Harvard Law Review, measured from 1999 to 2012, don’t work.

Most Internet citations occur in footnotes or in the text of dissenting and concurring judicial opinions. Overall, Internet links account for only a small fraction of all judicial citations—for example, less than 2 percent on average in the Texas court system, according to Texas Tech University law professor Arturo Torres, author of the fall 2012 article (PDF) “Is Link Rot Destroying Stare Decisis as We Know It? The Internet-Citation Practice of the Texas Appellate Courts.”

But as time passes, the number of nonworking links increases. Even recent links are vulnerable to rot. According to the Chesapeake Digital Preservation Group, a collaborative archiving program, the average life span of a webpage is between 44 and 75 days. The CDPG began collecting URL data for online law- and policy-related materials in 2007, and in its 2013 report (PDF) it stated that more than 50 percent of .gov links it archived no longer work just five years later. The CDPG notes that important legal materials are increasingly being “digitally born” and distributed online rather than published on paper, resulting in a “troubling trend” of transient legal information.

“I think it’s a big problem and getting worse—and it snuck up on us because things change incrementally in this area,” Zittrain says. “When links were first introduced into opinions, they were superfluous—icing on the cake. I think, over time, that’s really changed. More and more what’s being cited, as an example or as a source of something, may live only online and not as a part of a formal knowledge system.”

Such is the case for Harout Samra, an attorney at DLA Piper in Miami who specializes in international dispute arbitration and litigation. In his practice area, Samra frequently cites to international authority found only on the Internet—but he always downloads and prints the information to attach as an exhibit. “It’s a real problem that’s part of dealing with the Internet, whether in the context of making legal arguments to a judge, or whether it’s a judge at any level writing an opinion,” says Samra, who also co-chairs the ABA’s Technology for the Litigator Committee in the Section of Litigation. “And it’s not so much a unique problem to the law as it is a problem unique to the Internet and the speed of how things change.”

There are many reasons that links disappear, including webpage restructuring, domain changes, shuttered organizations and defunct servers. To counter link rot, researchers suggest ensuring that copies of the cited webpages are included with a pleading or opinion and using databases that permanently store the cited information.

Temple University law professor Ellie Margolis has written extensively about the use of online sources to support legal analysis. Margolis says what’s most important is that the public has access to cited information, whether in print or online.

“If lawyers are citing Web information, attach an appendix with the version of the website they’re referring to,” Margolis says. “If a judge is writing an opinion and citing to a source online, they should capture that at the time and not just assume the link and what it points to will be the same two years later when someone goes to look at it.”


The growing prevalence of Web references prompted the Judicial Conference of the United States to provide guidelines for judges on citing and maintaining Internet sources and hyperlinks in opinions. Suggestions include downloading cited Internet resources, and including them with opinions and in the court’s electronic case file system. The Supreme Court retains a print copy of Internet citations in the clerk of court’s case file, but that offers limited accessibility.

The 9th U.S. Circuit Court of Appeals at San Francisco is regarded as a model for judicial digital archiving, offering a public database of all 9th Circuit opinions issued from 2008 to the present containing links, along with a copy of the cited material as a PDF file. According to the court, the project “attempts to capture, as closely as possible, what the court was referencing at the time the opinion was released.” While these programs are steps in the right direction, legal observers say more comprehensive efforts are needed.

“We live in a media-rich world,” Liebert says. “The problem becomes: How do you print out a movie or MP3 file? It’s impossible. There has to be something in place that deals with this.” Liebert points to e-filing systems in place in courts across the country as an option. “It would not be that much of a stretch to add an electronic copy of websites or movies [to these systems], but at what point are we then running into problems of copyright?”

Zittrain and the Harvard Library Innovation Lab are trying to combat link and reference rot by building a permanent home for legal citations to online sources. Zittrain has created a coalition of more than 30 law libraries to preserve Web links through a database called The collaboration will store permanent caches of links upon request. Authors, editors and courts can use to maintain potentially ephemeral links on a public platform.

“I think [courts are] aware of the issue, and they’re doing exactly the reasonable thing given their posture and resources,” Zittrain says. “But they’re basically doing a Noah’s Ark for the coming bad years, like a seed bank, trying to store the stuff somewhere. It’s asking a lot of the courts to do that, but hopefully with something like Perma we’ll properly harness the resources of the great libraries of this country and the world to allow [courts] to achieve this sort of archiving and referencing.”

Liebert agrees that a collaborative and comprehensive effort can counter link rot, ensuring preservation of the past. “In the end, we are researchers. And as researchers, the validity and usefulness of information like this is so important,” she says. “If it’s disappearing off the face of the earth, the consequences are huge and we have to put measures in place that prevent this from happening.”

This article originally appeared in the December 2013 issue of the ABA Journal with this headline: “Missing Links: ‘Reference rot’ is degrading legal research and case cites.”

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