The court used to be a more decorous institution. A new computer analysis of about 25,000 Supreme Court opinions from 1791 to 2008 identified three trends that have transformed the court’s tone. The justices’ opinions, the study found, have become longer, easier to understand — and grumpier. The new study, to be published next year in the Washington University Law Review, is the work of Daniel Rockmore and Keith Carlson, computer scientists at Dartmouth College, and Michael A. Livermore, a law professor at the University of Virginia. It is part of a cottage industry...