re four years later einhorn was involved in a more genuine controversy with the producers of nancy mcclernan's play tam lin which resulted in legal action the controversy began when edward einhorn registered a derivative copyright on what he called a blocking and choreography script completely without my authorization after he had a fee dispute with my production partner a year later when i produced my play tam lin he sued me on the basis that i was violating his unauthorized derivative copyright the dramatists guild published my article on the case the strange case of edward einhorn v mergatroyd productions in its september october edition of the dramatist