SSRN has always had a strong orientation toward business and economics: the first four networks, in 1994, were Financial Economics Network, Legal Scholarship Network, Economics Research Network, and the Accounting Research Network. To help researchers navigate the hundreds of thousands of economics papers in the repository, SSRN allows authors to assign JEL codes—the American Economic Association classification system for the Journal of Economic Literature and EconLit (the leading index of articles in economics)—to their papers. In turn, researchers can use those codes to home in on papers of interest.
According to the American Economics Association's guide to the JEL system, codes beginning with "K" are for works about Law and Economics:
Covers studies about issues related to the intersection of law and economics. Studies emphasizing the economic analysis of law (equity or efficiency) should be classified here. While studies emphasizing the actual effects (empirical studies) of law on the performance of an economy, a sector or sectors of an economy, or individual agents should be cross-classified here and under the other appropriate category or categories. Studies about these subjects related to economic development should be cross-classified here and under O17, and those related to socialist and transitional economies (or other economic systems) should be cross-classified here and under P37 (or P48). Studies about the market for legal services should be classified under L84.
For example, K140, Criminal Law, "Covers studies about issues related to the intersection of criminal law and economics or economies." Examples are Doron Teichman, The Market for Criminal Justice: Federalism, Crime Control, and Jurisdictional Competition, 103 Mich. L. Rev. 1831 (2005), and Brenda Sims Blackwell & Clark D. Cunningham, Taking the Punishment Out of the Process: From Substantive Criminal Justice through Procedural Justice to Restorative Justice, 67 Law & Contemp. Probs. 59 (2004).
To use JEL codes in your searching, choose Browse by JEL code (an option available from the browse screen and the advanced search screen). Skim until you find an appropriate code, whether it's C2 (Econometric Methods: Single Equation Models) or K14 (Criminal Law).
excerpt from list of JEL codes
Once you select a JEL code, you can search within all the papers coded there.
It appears that many authors in law assign JEL codes even when the papers have little economic analysis. For example, the author of a paper about criminal law might assign K14, thinking that the code is for all of criminal law, not criminal law within Law and Economics. Indeed, of 4,124 papers listed under K14, only 298 had "economic" in their titles or abstracts. (This search was a few years ago—July 20, 2014—but I expect the pattern to remain.) So if you were using the JEL code to find law and economics, your search would be too broad. If you are really looking for law and economics, don't rely on the JEL Code alone: select a JEL Code and then search within the results for relevant terms.
On the other hand, some papers that are clearly about law and economics do not have JEL Codes. One highly downloaded paper without a JEL Code is: Eric Posner, Agency Models in Law and Economics, Clearly about law and economics! So do not think that using a JEL Code will retrieve all law and economics papers.
As in all research, thoroughness requires trying more than one approach.
Should all papers have JEL Codes? There is no requirement that they do. I sampled (in July 2014) the 100 most downloaded papers with the word "torts" in the title or abstract and the 50 most downloaded papers in the Law & Literature eJournal. Of the 100 torts papers, 55 had JEL Codes and 45 did not. The 50 law and literature papers split evenly, 25-25. I did not read the abstracts or the papers to see how deep the economic analysis was, but it seems clear that many authors use the codes even for papers with little or no economics. I think that shoehorning non-economic papers into the JEL framework dilutes the usefulness of the codes. A JEL Code is not necessary for a paper to have visibility and get hundreds of downloads. I recommend using the codes only for papers with economic analysis.