When the United Kingdom joined the European Economic Community on January 1, 1973, it brought Gibraltar with it — and Spain, which joined thirteen years later on January 1, 1986, suddenly found itself sitting at the same table as the territory it had been trying to reclaim since Utrecht. Legal scholar Peter Gold, in his study of Gibraltar's constitutional status, noted that European integration did something no siege or referendum had managed: it placed Britain and Spain inside a shared legal architecture where the 1713 treaty had no explicit standing. European integration introduced Brussels as a new legal actor, adding complexity to the sovereignty dispute between Britain and Spain. The Treaties of Rome, signed March 25, 1957, created the EEC; the Single European Act of 1986 pushed toward a single market, live January 1, 1993. Gibraltar was inside that market, but with a critical carve-out: it was excluded from the EU customs union and VAT area, a status that made it simultaneously European and anomalous. That anomaly generated friction immediately. The Schengen Agreement, signed June 19, 1990, abolished internal border checks across participating states. The UK never joined Schengen. Spain did. The land border between Gibraltar and Spain remained a hard checkpoint, highlighting the unique challenges Gibraltar faced within the EU framework. Spanish workers crossing daily faced queues that could stretch hours. Families divided by the border closure of 1969, only partially reunited after 1985, found that European freedom of movement applied everywhere except the one crossing that mattered most to them. In 2002, the Joint Sovereignty proposals emerged from talks between London and Madrid — a framework that would have shared governance of Gibraltar between Britain and Spain. The Gibraltarian response was immediate and overwhelming. A referendum held October 7, 2002, rejected the proposal by 98.5 percent. The reasons were direct: Gibraltarians saw joint sovereignty as a staged transfer, not a genuine partnership, and the 1967 precedent had already established that their democratic will carried legal weight. Spain's EU membership had not softened that calculation at all. EU membership transformed the Gibraltar dispute into a regulatory challenge within the EU framework, adding layers of complexity. The Treaty of Utrecht was temporarily sidelined, not because it lost legal force, but because both Britain and Spain were operating inside a regulatory framework that generated its own disputes — customs rules, border management, financial services passporting, fishing rights in the Bay. The battlefield shifted from military sieges and UN resolutions to European Court rulings and single-market directives. For you, Neil, tracking this story from Utrecht forward, that shift matters enormously: EU membership briefly transformed a centuries-old sovereignty dispute into a complex regulatory tug-of-war within Brussels. And when Brexit arrived, it didn't just reopen the old wound — it stripped away the institutional layer that had been covering it.