Miranda warnings enshrine the constitutional rights of custodial suspects against self-incrimination. However, the wording and sentence complexity of Miranda warnings and waivers vary dramatically from jurisdiction to jurisdiction. This study is the first extensive investigation of Miranda warning variations examining 560 Miranda warnings from across the United States. With Flesch-Kincaid reading comprehension as a useful metric, Miranda warnings varied from very simple comprehension (i.e., grade 2.8) to requiring postgraduate education. Miranda warnings are composed of five components (e.g., silence and evidence against you); marked variations were also observed in the comprehensibility of individual components. On average, the Miranda warning component on "continuing rights" requires a reading comprehension level six grades higher than the comparatively simple expression of the right to silence. Similar analyses were conducted on Miranda waivers. The content of these warnings differed on such issues as communicating (a) when access to an attorney would be granted (e.g., 45.9% specified only "during questioning") and (b) explicitly that indigent legal services were free (e.g., 31.8% directly informed suspects). Finally, the study identified representative Miranda components at different levels of reading comprehension as a template for further research.

Miranda warnings are remarkably heterogeneous in their language, length, and content. Past research has focused mostly on individual Miranda warnings. Lacking in generalizability, these studies have limited applicability to both public policy and professional practice. A large-scale survey by R. Rogers et al. [2007b, Law and Human Behavior, 31, 177-192] examined Miranda warnings from across the United States and documented striking differences in the length, content, and reading comprehension. In moving from single jurisdiction studies to nationally representative research, the replication of the Rogers et al. survey is essential. With an additional 385 general Miranda warnings, most of the original findings were confirmed; this replication allows Miranda researchers to use findings based upon nationally-representative warnings for their subsequent research. Beyond reading comprehension, the study makes an original contribution to the understanding of Miranda vocabulary that is often infused with abstruse words and legalistic terms. It provides the first analysis of sentence complexity, which affects both Miranda comprehension and retention. As a result of these analyses, preliminary guidelines are provided for increasing the comprehension and understanding of Miranda warnings.

Annually, more than 1.5 million juvenile offenders are arrested and routinely Mirandized with little consideration regarding the comprehensibility of these warnings. The current investigation examined 122 juvenile Miranda warnings from across the United States regarding their length, reading level, and content. Even more variable than general Miranda warnings, juvenile warnings ranged remarkably from 52 to 526 words; inclusion of Miranda waivers and other material substantially increased these numbers (64 -1,020 words). Flesch-Kincaid reading estimates varied dramatically from Grade 2.2 to postcollege. Differences in content included such critical issues as (a) right to parent/guardian input, (b) specification of free legal services for indigent defendants, and (c) statements of right to counsel in conditional terms. Recommendations for simplified juvenile Miranda warnings are presented.

A conservative estimate is that 695,000 mentally disordered offenders are arrested and Mirandized annually in the United States. Past research has focused almost exclusively on cognitive factors affecting the comprehension of Miranda rights. The current study broadens the scope by including diagnostic variables and by extending the investigation to basic elements of Miranda reasoning. A sample of 107 mentally disordered defendants was administered two research measures, the Miranda Statements Scale (MSS) and Miranda Rights Scale (MRS), in addition to standardized tests. Most defendants lacked good comprehension of all but the simplest (Flesch-Kincaid<6th grade) Miranda warnings. Defendants with the poorest understanding (i.e., comprehending about 25% of the warnings) had marked deficits in multiple domains including cognitive abilities (intelligence and comprehension) and general adjustment. Different background and clinical variables predicted defendants' abilities to generate reasons either to exercise or waive their Miranda rights.

Miranda vocabulary forms the essential foundation for Miranda comprehension and subsequent decisions to exercise or waive Miranda rights. The purpose of the current study is the development of the Miranda Vocabulary Scale (MVS), designed to evaluate key vocabulary words found in Miranda warnings and waivers across American jurisdictions. A preliminary list of MVS words was refined by expert ratings and by each word's discriminability between failed and good Miranda comprehension. Miranda and other measures were collected at multiple sites on 376 pretrial defendants. With further refinements, the MVS is composed of 36 words with excellent scale homogeneity and interrater reliability (r = .99). It also demonstrated good convergent and discriminant validity for cognitive abilities and psychological impairment.