Auditors and audit researchers consider decision aids important for overcoming biases and for improving the effectiveness and efficiency of audits (see Messier, 1995 for a review). Decision aids are used to increase judgment consistency, and, therefore, have potential to improve both the effectiveness and efficiency of audits. This study investigates three levels of justification requirements (no justification, unconditional justification, and justification of disagreement) to determine their effects on decision-makers' agreement with an aid and performance in decision-making. We find that an unconditional justification requirement leads to better performance when there is no decision aid, but leads to no better performance or increased agreement with the aid when a decision aid is present. Justification of disagreement with a decision aid, however, leads to increased agreement with the aid's advice in all conditions. We also find partial support that justification of disagreement leads to better performance than unconditional justification. For those who would like to see a decision aid have more influence, justification of disagreement with a decision aid could be an easily and economically implemented management policy or software design component.