Can ISPs legally block Tor traffic in the United States in 2025?

1. A fractured regulatory landscape hands ISPs discretion — and uncertainty

A January 2025 federal appeals court decision struck down core net neutrality rules, finding the FCC exceeded its authority and thereby opened the door for ISPs to treat types of traffic differently, potentially including blocking or throttling anonymity services ^{[1] [2]}. That ruling does not specifically name Tor, but it removes a federal-level bar that had constrained ISP discrimination against particular protocols and services. At the same time, several states have enacted their own net neutrality statutes, creating a geographic patchwork: where state rules remain in force, ISPs may be restricted from blocking traffic; where they do not, ISPs have greater latitude ^{[2] [5]}. The practical effect is legal uncertainty: an ISP’s ability to block Tor depends on which legal regime governs the subscriber and which court precedent applies.

2. Court orders and intellectual-property cases show blocking can be compelled

U.S. courts have previously issued injunctions compelling ISPs to block access to specific infringing sites and services, demonstrating that judicially mandated blocking is legally feasible when tied to copyright enforcement ^[3]. Those orders were case-specific: they targeted particular domains or services alleged to facilitate piracy, not anonymity networks broadly. This precedent shows courts can and will use equitable powers to require intermediaries to take technical measures, but it does not automatically translate into a general authority to force ISPs to block Tor across the board. Any attempt to compel blocking of Tor would likely be litigated on whether the requested remedy is narrowly tailored, technically feasible, and consistent with constitutional or statutory protections.

3. Europe’s cautionary rulings inform but do not control U.S. outcomes

European Court of Justice rulings that bar broad mandatory filtering and monitoring of traffic underline legal limits on sweeping ISP obligations and stress balancing intellectual property enforcement with privacy and free-speech rights ^{[6] [7]}. While these decisions are persuasive for policy debates, they do not bind U.S. courts. Still, they illustrate judicial skepticism toward blanket filtering regimes and provide a comparative framework critics use to argue against wholesale blocks of privacy-preserving systems like Tor. In U.S. litigation, judges may similarly weigh fundamental rights and technical feasibility when evaluating requests to require ISPs to block anonymity services.

4. ISP policies and enforcement practices vary — operational reality matters

Independent of courts and regulators, ISPs maintain diverse contractual and abuse-response policies: some explicitly permit running Tor relays or exit nodes under conditions, others prohibit Tor services or suspend accounts after abuse complaints ^[4]. These private policies mean ISPs can and do terminate or limit Tor-related operations under their terms of service even absent a court order. Thus, in practice, Tor connectivity can be curtailed through commercial enforcement or abuse-handling processes. Advocacy groups warn that site-blocking legislation or enforcement mechanisms can be overbroad and easily misused, and technical workarounds (VPNs, alternative DNS) can both mitigate and complicate enforcement efforts ^[8].

5. The bottom line: legal outcomes will be decided case-by-case and may escalate

The combined evidence shows no single bright-line answer: ISPs can block or be ordered to block traffic in certain legal contexts, particularly under weakened federal net neutrality and in response to specific court injunctions tied to unlawful activity, but state laws, contractual terms, and constitutional considerations constrain that power in other contexts ^{[1] [3] [4]}. Expect litigated tests and political battles to continue: net neutrality advocates may seek Supreme Court review or new federal legislation, states will continue divergent regimes, and courts will parse remedies narrowly when fundamental rights or broad filtering are implicated ^{[2] [8]}. For users and operators of Tor, the practical risk in 2025 is uneven access rather than a single, settled rule.