Calls to reconsider Poland's participation in the Schengen system strike at one of the most tangible benefits of EU membership. Supporters of tougher border policies argue that national governments must regain greater control over migration and security. Critics warn that leaving or suspending Schengen participation could hurt trade, travel and millions of ordinary Poles. The debate also exposes the deeper confrontation between nationalist and pro-European visions of Poland. Few issues combine sovereignty, migration and everyday economic consequences so directly.