Objectives. The Scottish legal system differs from that which pertains in the rest of the United Kingdom, for example, there is no standard police caution to administer to suspects in Scotland. The absence of a standardized caution may result in suspects being presented with a caution which is both semantically and syntactically complex. Over the last 30 years the central role given to an individual's appreciation that he/she has the right to remain silent has diminished when evaluating whether a confession has been obtained fairly. This study examines the extent to which offenders understand the caution and the factors which influence their level of comprehension.Methods. A Scottish Comprehension of Caution instrument was developed. One hundred convicted young offenders were assessed using this instrument, a short form of the Wechsler Adult Intelligence Scale Revised and a range of measures of criminal experience and attitudes.Results. The overall level of comprehension was low: while 89 per cent claimed to fully understand the caution only 11 per cent were considered to have a complete understanding. Level of understanding was linked to cognitive functioning and not linked to demographic or criminal justice variables.Conclusions. It is argued that the semantic and syntactic complexity of the caution is a significant barrier to understanding. This may reflect the fact that the archival function of legal language takes precedence over its communicative function.