Understanding precedents in a temporal context of evolving legal doctrine

In evaluating the precedential strength of a prior case, skilled attorneys take account of how the holdings of the case have been treated in subsequent decisions. This paper describes the process by which a formerly strong precedent may be weakened by over time, identifying five reasoning patterns by which attorneys may predict that a most-onpoint case is likely to be explicitly or implicitly overruled. We consider the requirements for implementing this form of analysis in a case-based legal reasoning system, proposing an extension to earlier schemes for case representation, and outlining an evidential reasoning algorithm to compute the degree to which the holdings of a prior case have been weakened.