Purpose. Numerous wrongful convictions have brought into question the ability of judges and juries to accurately evaluate the credibility of witnesses, including defendants. Dangerous decisions theory (DDT) offers a theoretical framework to build our understanding of the decision-making process that can culminate in such injustices.

Arguments. According to DDT, the reading of a defendant's face and emotional expressions play a major role in initiating a series of ‘dangerous’ decisions concerning his/her credibility. Specifically, potent judgments of trustworthiness occur rapidly upon seeing a defendant's face, subjectively experienced as intuition. Originally evolved to reduce the danger to the observer, the initial judgment – which may be unreliable – will be enduring and have a powerful influence on the interpretation and assimilation of incoming evidence concerning the defendant. Ensuing inferences will be irrational, but rationalized by the decision maker through his/her subjective schemas about trustworthiness and heuristics for identifying deceptive behaviour. Facilitated by a high level of motivation, a non-critical, tunnel vision assimilation of potentially disconfirming or ambiguous target information can culminate in a mistaken evaluation of guilt or innocence.

Conclusions. Empirically based education and responsible expert testimony could serve to reduce such biases and improve legal decision-making.