A more thorough explanation:

Empirical legal studies, also known as ELS, is a type of research conducted by law professors using social science research methods to study legal issues. This type of research is different from traditional legal research because it focuses on using data and statistics to understand legal issues.

For example, a law professor might use ELS to study the effectiveness of a particular law or policy. They might collect data on how the law is being implemented and how it is affecting people's lives. They might also compare this data to similar laws in other countries to see how effective the law is compared to other approaches.

The two leading journals in this field are the Journal of Legal Studies and the Journal of Empirical Legal Studies. These journals are unique because they use a peer-review process to ensure that the research published in them is of high quality.