A "preemption check" is the process through which you can determine whether your proposed note or thesis topic has already been covered. Doing a preemption check can both ensure that your topic is original and give you a head start on finding relevant sources for your topic.
If you are writing a note for your journal, be sure to check in with your journal's editors, as they may have a preemption checklist or policy they would like you to follow. If you would like additional guidance on how to design your preemption check for your topic, please reach out to a reference librarian at referencedesk@law.columbia.edu.
To browse and search for law journal articles by subject, we recommend starting with legal periodical indexes. The two major legal periodical indexes are LegalTrac and Index to Legal Periodicals and Books. These databases can be accessed through our Databases and Indexes page. Both LegalTrac and Index to Legal Periodicals and Books will allow you to search by subject and within abstracts, thereby providing a more focused preemption check starting point than a normal full-text search.
More current indexing of legal periodicals is available via Current Index of Legal Periodicals, which is available through HeinOnline. If your topic concerns foreign, comparative, or international law, you'll want to check out Index to Foreign Legal Periodicals, also available through HeinOnline.
HeinOnline's Law Journal Library provides full-text PDF copies of over 3,000 law journals dating back to their inception. You can use HeinOnline to either (1) find the full text of specific journal articles mentioned in the legal indexes above, or (2) run a full-text search for keywords related to your topic. HeinOnline also provides some useful advanced search tools, including their Keyword Search Builder (with which you can weight some keywords over others) and their Venn Diagram Search (which helps visualize which articles are related to which search term). Finally, HeinOnline works as a citator, providing links to both articles cited by a relevant article as well as articles citing to a relevant article.
You can also run full-text searches on Westlaw Edge and Lexis+ to find treatises, practice guides, and legal encyclopedia articles on your topic. While these databases also contain the full text of law journal articles, their coverage is not as extensive as HeinOnline's.
If your topic is an interdisciplinary one, you'll want to expand your preemption check to include non-law periodicals. The best way to run full-text searches for non-law journal articles is through CLIO and Google Scholar.
CLIO's Articles+ search looks through a large database of mostly full-text journals and newspaper databases like JSTOR and Factiva, often providing you with a proxy link to the full text of any relevant article.
Google Scholar allows you to then check to see what other articles have cited the article you found.
Once you have checked to make sure no periodical has published something on your topic, SSRN can provide some advance warning of articles that have not yet been published. Most law-related articles in SSRN can be found in their "Legal Scholarship Network," which they classify under "Social Sciences." Running some searches on this database can let you know if your topic is in danger of being covered in a soon-to-be-published article.
You can also set alerts on Westlaw, Lexis, or the Current Index to Legal Periodicals so that you receive an email if any newly published article relates to your topic.
If you would like assistance setting up such alerts or if you would like additional help with your preemption check, please reach out at referencedesk@law.columbia.edu.