Justin Trudeau has promised that, if elected prime minister, this will be our last election under First-Past-the-Post (FPTP). It's a bold pronouncement but the electoral system is fundamental to our democracy, so the plan to bring it about must be beyond reproach. Is it?In recent years, three provinces have tried to change their electoral system—BC, Ontario and PEI—and all have failed. The BC and Ontario Citizens' Assemblies offer a particularly useful lesson for Trudeau.The Assemblies tackled three basic questions. First, is FPTP unfair and should it be changed? Second, would more proportional representation be fairer? Finally, can they design a new system that they all agree upon? Both Assemblies replied affirmatively to all three.Now, if we believe in democracy, it is hard to disagree that citizens are eminently qualified to pronounce on the fairness of their electoral system (Question 1). Moreover, if they judge that a system that results in more proportional representation would be fairer (Question 2), who's to disagree? However, asking citizens to devise such a system (Question 3) is more controversial.In Ontario, when the Assembly's proposed system was put to a referendum participants could barely explain how it would work or why it was chosen. In the end, Ontarians were confused and skeptical of the model and it is widely agreed that the lack of clarity and of a credible spokesperson killed the proposal.BC had two referendums. The first was in 2005 and came within a hair of passing, so a second one was held in 2009, but this time support dropped sharply. The reasons are less clear, but here too it seems to be a mix of complexity and the lack of credible leadership on the issue.The lesson is that, while people may trust their fellow citizens to deliberate over values, they are less willing to trust them on expert matters. Engagement processes should be careful to distinguish value questions—such as the overall fairness of the system—from technical ones, such as how a voting system should be designed. On the latter, the issues can get very complex very quickly and an assembly of citizens may have a hard time sorting through them.The BC and Ontario Assemblies could have addressed this by limiting citizens' role to the first two questions (and perhaps a bit of the third one) and then bringing in a panel of, say, 15 experts from across the province to solve the design issues. Panel members would have been instructed to check their personal preferences at the door; and to work as a team to design the best possible system, based on the Assembly's answers to Questions 1 and 2.I believe they would have done so. Moreover, once they had finished their work, they would have been able to stand up in public, shoulder to shoulder, and assure citizens that they had designed the best system possible. This assurance would have had a high degree of credibility and gone a long way to assuaging citizens' concerns. The panel would have brought a degree of legitimacy to the proposed system that, in the other approach, was lacking, which brings us to Trudeau.He has proposed an all-party committee to investigate the options around electoral reform, but choosing a model could be highly controversial. While Trudeau favours ranked voting, the NDP wants some form of mixed system, including both FPTP and proportional representation, as do the Greens. The Conservatives want the status quo. The process will include broad public consultations, but public opinion is also likely to be divided. If the committee fails to agree on a model, how will the final decision be made?If there were a majority Liberal government, Cabinet could make the decision, but people who disagreed with its choice would be likely to see the process as unfair, especially if the Liberals had a majority on the committee, as seems likely.In any event, the more likely scenario is a minority Liberal government. Given their interest in electoral reform, the NDP might be willing to work with the Liberals on this, but only if they were confident their option would be treated fairly. There is a way.Over the last year, one of the most refreshing aspects of Trudeau's approach to decision-making has been his willingness to introduce neutral, third-party processes to ensure appointments, say, to the Senate or the judiciary are legitimate. Why not take a similar approach here?To design the right system, we need to be clear on the issues. A credible process could be designed to let the committee engage Canadians in a discussion to identify and prioritize their concerns with the existing system. The committee's mandate would be to help Canadians speak their minds and report on the findings, but it would stop short of recommending a specific option.Following the release of the report, Trudeau could work with the other party leaders to strike a highly qualified, nonpartisan committee to design the best system possible, based on the committee's findings. The committee would then present this to the government who, presumably, would act on it.Of course, Liberals and the NDP would have to be willing to let Canadians articulate their concerns; and then trust the expert committee to translate this into the right option for Canadians. If they did, this division of labour between citizens, experts and decision-makers would give the process a very high degree of transparency and legitimacy. Any of the parties who participated in the process would oppose it at their peril.Dr. Don Lenihan is Senior Associate, Policy and Engagement, at Canada 2020, Canada's leading, independent progressive think-tank. Don is an internationally recognized expert on democracy and Open Government. His recent projects include chairing an expert group on citizen engagement for the UN and the OECD; and chairing the Ontario Open Government Engagement Team. The views expressed here are those of the columnist alone. Don can be reached at: [email protected] or follow him on Twitter at: @DonLenihan