Law, Language, and Aboutness: Diaz v. United States as Case-Study

Abstract

The Supreme Court’s recent decision in Diaz v. United States is a simple interpretive dispute concerning when expert testimony is ‘about’ a defendant’s possession of mens rea conducted by justices who are avowedly textualist and yet reached diametrically opposite conclusions. While the court reached the right result in permitting testimony concerning behavior of members of a class including the criminal defendant, the rationale it offered is at best incomplete and at worst incorrect.

This essay introduces into legal analysis the rigorous study of aboutness in analytic philosophy, which is used to augment, rather than attack, the textualist analyses offered by the justices. The essay develops the tools of aboutness in a straightforward way that should serve as a primer for those interested in the technique and its value – a group which should definitely include those interested in textualist interpretation. 

Taking aboutness seriously elegantly justifies the correct result in Diaz. The essay concludes on the speculative note that aboutness can be used to resolve other intra-textualist disputes, such as the thorny one in Bostock v. Clayton County. Thus, attending to aboutness allows us to cleanly explain the meaning of Federal Rule of Evidence 704, and it may lead to further cogent explanations where thorny disputes have pervaded the law even against the common ground of shared textualism.

Keywords: textualism, aboutness, United States v. Diaz, Federal Rules of Evidence, Rule 704