This chapter explores the evolving constitutional meaning of freedom of expression in the digital age, focusing on the regulatory and judicial dilemmas posed by the proliferation of disinformation. It begins by tracing the historical and comparative foundations of free speech, emphasizing its dual role as both an individual right and a structural precondition for democratic self-governance. In doing so, it contrasts the U.S. model—centered on the near-absolute protection of speech under the First Amendment—with the European approach, which allows for more calibrated balancing with other constitutional values, such as dignity, equality, and democratic integrity.The discussion then turns to the challenges raised by the contemporary information ecosystem, where digital platforms, engagement-driven algorithms, and generative AI reshape the circulation of ideas and exacerbate the spread of disinformation. Disinformation is conceptualized not merely as a legal or factual problem, but as a phenomenon at the intersection of technological amplification, cognitive manipulation, and democratic vulnerability. Particular attention is devoted to the European Union’s three-phase regulatory trajectory: from strategic communication (phase one), to soft law and self-regulation (phase two), and finally to a more robust co-regulatory and legislative framework (phase three), embodied in instruments such as the Digital Services Act, the European Media Freedom Act, and the Regulation on Political Advertising.