In May 2013, the American Psychiatric Association (APA) published the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in order to bring America's clinical professionals in concert with the World Health Organization's (WHO) international classifications, notably the ICD-10-CM. This effort was met with considerable resistance and changes were delayed until November 2015. Major social-cultural differences between the United States and its European and other North American partners (Canada and Mexico) poses challenges in critical forensic areas such as the clinical/legal assessment of death qualified offenders – a status unique to the USA.

To articulate the clinical/legal differences between the previous DSM's (III; III-R; IV) and the DSM-5 and how the new language provides greater ambiguity in defining the mental status requirements for Mens Rea – competence to understand one's actions.

Present the major legal issues surrounding the US death penalty and brought before the US Supreme Court including: Furman v. Georgia (1972); Greg v. Georgia (1976); Jared v. Texas (1976); Proffit v. Florida (1976); Adkins v. Virginia (2002); Roper v. Simmons (2005); Miller v. Alabama (2012): … and legislative actions such as Rosa's Law (Public Law 111-256; 2010).

Advocacy groups pushed Rosa's Law to mental retardation with – intellectual and developmental disability. This change is reflected in the DSM-5 whereby mental retardation (MR) was once relegated to axis II, is now classified under intellectual disabilities (ID) given the impression that it is a transitory (correctable) and not a fix (organ disability) clinical condition.

The author has not supplied his declaration of competing interest.