Although most court cases involving copyright protection of the user interface appear to have been decided correctly on their facts, the language of the decisions has left uncertainty as to the scope of protection.
Todd D. Daubert,
Copyright, Potential Markets, and the User Interface: Defining the Scope of the Limited Monopoly,
55 Law and Contemporary Problems
Available at: https://scholarship.law.duke.edu/lcp/vol55/iss2/18