United States lawmakers demonstrated an increased appetite for regulating technology giants when they grilled Facebook chief executive Mark Zuckerberg about privacy this past week. But the future of Facebook's relationship with its 2 billion users is less likely to be determined from the halls of Congress than it is from an unassuming 18th-century townhouse in Ireland's capital packed with lawyers, technology experts and gumshoe investigators.

Europe has been moving aggressively to impose order on the tech space. Already, it has inflicted painful penalties on Apple and Google for their business practices.