The Lake County Circuit Court Case Files Index, 1840-1898, is available at the Illinois State Archives website. A printed copy of this index is available in book form at the genealogy room at Fremont Public Library in Mundelein.
Search by both plaintiff and defendant. Be sure to read the history of the court and the instructions on the page. Those items are helpful.
Copies of files found can be obtained from the:
Illinois Regional Archives Depository
c/o Regional History Center
Founders Memorial Library
Northern Illinois University
DeKalb, IL 60115
Phone: (815) 753-1807
For Lake County naturalization information see the naturalization link on our home page.