The collapse of Oliver Plunkett’s Dundalk prosecution, followed by his transfer to London, highlights how jurisdiction could shape justice during the Popish Plot crisis. Local proceedings allowed absent witnesses and rebuttal evidence to matter, whereas English political pressures created a different setting. This raises a broader question about the relationship between legal procedure, central authority and confessional fear. How should we interpret the contrast between Dundalk’s failed case and the later London trial: as evidence of differing legal cultures, political manipulation, or the fragility of protections for Catholics across the Stuart kingdoms during this period of intensified religious suspicion overall?