Searching Westlaw and Lexis for legal articles is not enough. Neither has sufficient coverage to properly conduct a preemption check. A good search starts with indexes.
Remember, your goal is to check everything ever written on your subject - you have to cast a wide net to catch everything.
Indexes allow you to search large numbers of law review or journals simultaneously. Between the various indexes, you can be certain that you have searched EVERY law review or journal's publication history. Additionally, they provide complete citations to articles making it easy to find the full-text article. Indexes use subject headings or topical headings to sort the articles for you. This makes it easier to find the articles that discuss a topic in depth rather than just mention your subject briefly.
Full-text databases are great for find the actual article you wish to read to determine whether you are preempted. Their lack of coverage - none of them have close to everything published - makes dependence on them in a preemption check very risky. Not every legal publication appears in Westlaw, Hein, or Lexis and, even for those that do, the full run of the publication might not be available.
Index to Legal Periodicals and Books – Full Text indexes more than 1,100 legal journals, law reviews, yearbooks, institutes, bar association publications, university publications, and government publications. In addition to journal articles, it also includes coverage legal symposia, jurisdictional surveys, books, and court decisions. Coverage extends to the U.S., Canada, Great Britain, Ireland, Australia, and New Zealand.
Index to Legal Periodicals Retrospective is an archive index covering 880 legal periodicals published in the United States, Canada, Great Britain, Ireland, Australia and New Zealand between 1908 and 1981.
LegalTrac provides indexing and selective full-text for more than 1,200 major law reviews, law journals, specialty law and bar association journals and legal newspapers.The database offers coverage of federal and state cases, laws and regulations, legal practice and taxation, as well as British Commonwealth, European Union, and international law.
You’ll need to consult the Index to Foreign Legal Periodicals if your topic involves foreign law. It provides a subject index to around 600 legal journals published worldwide. It provides in-depth coverage of public and private international law, comparative and foreign law, and the law of all jurisdictions. IFLP also analyzes the contents of approximately fifty individually published collections of legal essays, Festschriften, Mélanges, and congress reports each year. It covers from 1984 to the present.
On Westlaw, you should search the Current Index to Legal Periodicals. It provides a weekly list of new law periodical articles. New articles will probably appear here before any other index picks them up. Make sure to set up WestClip alerts! You’ll need them later.
When you find an article, you can look up the full text in one of three databases. In the rare event that you cannot access a full-text version of an article via these databases, you can make an interlibrary loan (ILL) request via the library's website.
HeinOnline’s Law Journal Library as well as Westlaw or Lexis’s databases. Hein is by far the most complete. Save your searches in your MyHein account so it will be easy to re-run the searches later.
On Westlaw, you should search the Law Review and Journals database under Secondary Sources. Make sure to set up WestClip alerts! You’ll need them later.
Lexis also has a Law Review and Journals database (under Secondary Materials). Turn on alerts for the searches you’ve run!
Working papers are articles that aren't published yet. To prevent a nasty preempting surprise while you are writing, you should search for relevant working papers in your initial search. None of these databases are comprehensive and their search capabilities vary in sophistication.
SSRN currently has more than 880,000 abstracts including working papers, articles that are accepted for publication but not yet published, and older articles.
Bepress Legal Repository contains working papers and pre-published works.
Google Scholar searches will currently (August 2019) include SSRN, BePress, JSTOR, and EBSCO information. However, that can change at any time. To check current coverage of a specific source in Google Scholar, search for a sample of their article titles in quotes.