This article presents a new perspective on online communities as a composition of diverse experts arguing in front of an audience. The paper is based on a netnographic study of social media activism protesting the obstruction of justice in the wrongful conviction of Roman Zadorov for the murder of Tair Rada, a conviction from which he was ultimately acquitted. The study demonstrates that some of the experts that argue in these online communities are akin to experts admissible in court, ranging from people connected to the case to regional insiders, expert witnesses, and circumstantial witnesses. However, other participants, not admissible in court, include two types: “laypersons” with extensive case knowledge, and people relying on supernatural insights. While this study reveals significant roles of lay and expert participants in online communities centered on justice issues, its insights are derived from a particular legal case. Therefore, findings may not generalize across all online communities but may be particularly relevant to communities that focus on high-profile cases where public scrutiny invites expert and ‘pro-am’ contributions.