Nicholas Tsui, How Similar Is Too Similar: The Predictability of Court Decisions in Musical Lyrics Copyright Cases, 62 J. Copyright Soc'y 307 (2015).
The author finds that despite the various ways in which different courts have interpreted the "substantial similarity" test in copyright infringement cases involving lyrics, the similiarity judgments in courts throughout the country were actually quite consistenent. The author states that he was able to accurately predict the court's outcome over 90% of the time using a simple similarity metric that counted overlapping words, phrases and lines. "My results indicate that courts' decisions on substantial similarity follow a relatively simple pattern analysis that while fact-specific was not so nuanced as to be unpredictable."