Purpose: The purpose of this paper is to explore how legitimizers invest in their approach to meet the suspicion of being a one-sided advocate. Design/methodology/approach: A multiple case study of four public sector decisions, based on a comparative argumentation analysis of two consulting reports in each case, one written by a legitimizer and one by a devil's advocate. The findings of the document analysis are triangulated with author interviews. Findings: Consultants acting as legitimizers are often suspected of being political allies of a decision maker. To neutralize their reputation as hired guns, these consultants invest in being seen as impartial by making their research approaches transparent and their argumentation balanced to increase their credibility in the eyes of stakeholders, which is necessary to execute their central task: legitimizing a major decision. Research limitations/implications: The number of four cases could limit the possible variation within the legitimizer role. Further research could therefore explore under what conditions consultants are willing to argue more one-sidedly as "advocates". Practical implications: Practitioners, such as consultants or decision makers, can apply the approach used in this research to make their method more transparent and to balance their argumentation to get commitment from stakeholders, while legitimizing a decision. Originality/value: The paper nuances the view on the legitimizer role of consultants in previous studies, by exploring how their arguments are more balanced and transparent than assumed and how they try to contribute to their clients' decision-making process. © Emerald Group Publishing Limited.