Glass artist Dale Chihuly is suing two glassblowers, claiming they are copying his designs. “How does an artist go about proving — or disproving — copyright infringement? How do you differentiate between Chihuly’s influence on other glass artists and artistic plagiarism? Can he claim exclusive rights to designs that are modeled on things such as Navajo blankets and sea life? And what does it mean for the world of art glass?”