Professor Michael D. Murray of Valparaiso University Law School has published The Promise of Parentheticals: An Empirical Study of the Use of Parentheticals in Federal Appellate Briefs, Legal Communication & Rhetoric: JALWD, 10, 229-263 (2013).
Here is the abstract:
This Article on current practices in advocacy and briefing reports an empirical study of the use of parentheticals in federal appellate court briefs submitted between February 1, 2011, and July 31, 2011. The study was designed to answer the question: How are parentheticals currently used for rhetorical purposes in appellate briefs to explain a synthesis of authorities? The study proves that parentheticals currently are used beyond a simple informational function in citation forms for four rhetorical purposes: (1) to quote and highlight portions of authorities (“quotation” function); (2) to explain and illustrate the principles induced from a synthesis of authorities (“explanatory synthesis” function); (3) to explain and illustrate the effect and operation of public policies underlying the law in multiple authorities (“public policy synthesis” function); and (4) to explain and illustrate the narratives of success or failure among multiple cases in which the law was applied to produce a concrete outcome (“narrative synthesis” function). Parentheticals in synthesis are used at a significantly higher rate that the other common method of communication of information about multiple authorities in legal analysis known as textual, case-to-case analogical reasoning.