If the phrases "most cited" or "impact factor" immediately catch your attention, you are not alone. Citation analysis (in which the influence of a particular publication is measured by how many subsequent publications have cited to it) remains a fashionable method for determining the influence of a particular law review article or legal journal. Although many scholars question the validity of such studies, their popularity endures.
Of course, you can always use Shepard’s and KeyCite to gauge the scholarly impact of a particular law review article citation, at least for articles published after 1980 (the cutoff date in Lexis and Westlaw for the full text of most law journals). For more historic legal articles, researchers might locate some citation metrics in the Social Sciences Citation Index on Web of Science (http://library.duke.edu/metasearch/db/id/DUK01574), although their coverage extends back to only 1956 and includes only selected law reviews. Fortunately, HeinOnline (http://library.duke.edu/metasearch/db/id/DUK00693) has jumped into the fray with its new social indexing tool, announced last month: http://heinonline.blogspot.com/2008/10/heinonline-introduces-concept-of-social.html.From Hein's original blog post:
For example, when you run a search for "Right to Privacy" across the titles in the Law Journal Library in HeinOnline, you will be able to determine how many times each result has been "cited by" other scholarly law review articles in HeinOnline. This allows you to view articles that have had a heavy influence or high impact on the subject you are searching. From here, you can then view the law review articles that cited this article to further your research in the given subject area. This research approach is easy, using simple links available in HeinOnline.The "future enhancement" of an option to sort article results based upon the number of subsequent citations in other articles is now active in HeinOnline [update 11/7: see new blog post at http://heinonline.blogspot.com/2008/11/scholarly-approach-to-social-indexing.html]. Hein’s Law Journal Library dates back to volume 1 for most of the law reviews in the United States, making this new feature a powerful resource for locating the most influential scholarship on a particular legal topic. To test it out, run a search in the Law Journal Library of HeinOnline and on your result page, choose Sort By: "Number of Times Cited" from the drop-down menu.
Future enhancements in the Law Journal Library will allow you to sort your results based on the number of times the articles are cited, thus bringing the most cited articles to the top of your search results list.