Try searching in NUsearch, the library's search tool, in the following way, and for Legal Systems, try a similar keyword search, such as:
"legal system" OR "rule of law" AND "united states" OR america*
Then limit your dates, formats, online availability, etc. with the facets to the left.
Try searching in HeinOnline, which provides access to a PDF collection of legal research materials, including law journals, and a wide range of primary sources on the history of Anglo-American law. Below is an example search: