Justia guest columnist, Cornell law professor emeritus, and former dean of Cornell Law School Peter W. Martin explores how citation format can be used to expose the true parentage of a case law collection, such as that of Westlaw, LexisNexis, Bloomberg Law, and other case law database services. Martin describes his methodology and calls attention to the existence of differences among the major database services. He questions whether these differences even matter to a majority of practitioners, judges, and librarians but cautions that for the sake of authenticity and reliability, they perhaps should matter.