AbstractIt is commonly claimed there is a crisis of expertise in liberal democracies and that experts who provide evidence‐based policy ideas have become widely distrusted. This paper reconsiders the nature of this perceived crisis in policy advisory systems. The literature has identified four reasons for this trend—politicisation, diversification, diminished policy capacity, and populism. Building on these claims, this paper suggests that the contestability of policy advice has been the key underlying shift in policy advisory processes. Contestability can be positively useful for testing the robustness of policy proposals. However, if the policy debate has no evidentiary standards, the contest becomes a clash of opinions and slogans. Hence, several approaches have been proposed to strengthen the role of professional expertise and improve the quality and legitimacy of evidence‐informed policymaking. One approach is the rebuilding of bureaucratic capacity to provide evidence‐informed policy advice. However, a technocratic–elitist style that invokes scientific authority would be difficult to sustain politically in relation to complex issues affecting citizen well‐being. A second approach is to improve stakeholder engagement and to enhance respect for the expertise embodied in ‘lived experience’. Thus, rebuilding trust and legitimacy may require broadening the range of relevant expertise through multi‐stakeholder approaches.Points for practitioners Types of expert policy advice have evolved and diversified, with many sources and channels both inside and outside government Contestability of policy advice has become more widespread Public service policy capacity has arguably been weakened through outsourcing, use of consultants, interest group lobbying, and the growing influence of ministerial advisors Evidence‐informed advisory systems have been challenged by fast decision‐making, wicked problems, media misinformation, and populist slogans Rebuilding capacity and trust in high‐quality policy systems requires new thinking, including more inclusive processes and a wider view of relevant expertise.