Ho v. Taflove is a Seventh Circuit case about the copyrightability of scientific data. In 2011, the Seventh Circuit affirmed a 2009 decision of the United States District Court for the Northern District of Illinois holding that the expression of ideas can be copyrighted but not the ideas themselves (the idea-expression divide). The plaintiffs alleged that the defendants violated the copyright law of the United States by publishing equations, figures, and text from research materials that the plaintiffs had produced. They also alleged that Illinois state laws were violated by publication of the materials. The district court granted summary judgment against the plaintiffs. The appeals court confirmed the judgment, concluding that the research materials were unprotectable ideas under the merger doctrine of copyright law, and that the claims of state law violations had no merit and were superseded by the Copyright Act. Background Seng-Tiong Ho and Allen Taflove were professors of engineering at Northwestern University, where Yingyan Huang and Shi-Hui Chang were graduate students. The plaintiffs, Ho and Huang, alleged that in 1998 Ho formulated a "4-level, 2-electron atomic model with the Pauli exclusion principle for simulating the dynamics of active media in a photonic device." Within a year Ho had completed the mathematical derivations of his model, notes and equations of which were hand-written in about sixty-nine pages. With permission from Ho, Huang briefly mentioned some results from the research in a conference paper published in 2001, and published the results in full in her 2002 master's thesis. The plaintiffs alleged that Ho gave another of his graduate students, Shi-Hui Chang, the task of creating a computer simulation of the model, giving him both access to Ho's handwritten texts and experience working with the model. Due to programming errors, Chang could not simulate the model. In 2002, Chang left Ho's research group and joined that of Taflove. In 2003 and 2004, Taflove and Chang submitted, and subsequently published, two articles directly related to the model. Some figures in Huang's master's thesis were included in these publications. The defendants did not attribute any published content to plaintiffs. The plaintiffs alleged that when Ho attempted to publish a paper about the model in 2004, his submission was rejected on the basis that the work had already been published, i.e., the articles published by Taflove and Chang. In 2007, the plaintiffs received certificates of copyright for Ho's notes describing the model and