Good decisions are based on experience and knowledge. in a non-hierarchy working environment a group can make better decisions when they factor in the experience and knowledge, each participant has in fields relevant to the topic discussed.
To be able to factor knowledge and experience in decision making, you need to define which fields are the most common and relevant to your organization and maintain this list. On top of the list of domains, you should have a mechanism to continuously evaluate people and maintain their knowledge and experience in each field. The process and the data must be transparent and gain people trust!
Once you have calculated merit for each person, you can use it in any conflict resolution. If you find yourself in a disagreement, factor merit into each person vote and respect the results.