Is Tor legal in the US? What the law says

As of November 2026, using Tor is legal in the United States. US government agencies have helped pay for it since 2001, and the State Department is among its current funders.^[1] A federal cybersecurity advisory, written with the FBI, recognises legitimate reasons to use it.^[2] What you do over Tor is still covered by the law.

Below: where Tor came from, what stays illegal, how investigators have identified Tor users in real cases, what your internet provider can see, and what to know before running a relay. For how Tor works, start with What is Tor Browser?

Did the US government create Tor?

Partly. The idea behind it, onion routing, came from researchers at the US Naval Research Laboratory in 1995. Roger Dingledine, who worked with one of them in the early 2000s, named the project Tor, and the network launched in 2002 with its code released as free, open-source software.^[3] The Electronic Frontier Foundation (EFF), a digital-rights group, began funding the work in 2004, and the Tor Project became a US nonprofit in 2006.^[3]

Federal money has been part of its funding from the start. The Tor Project’s sponsor list shows DARPA and the Office of Naval Research funding it through the Naval Research Laboratory from 2001 to 2006, years of National Science Foundation grants through universities, and the State Department among its current supporters.^[1] In its 2023–24 financial year, which runs from July to June, about 35% of the Tor Project’s revenue came from US government funds, down from 53.5% in 2021–22.^[4]

Does that money give Washington control? The Tor Project says its government funding always comes through a highly competitive bidding process, and that it designs and controls the projects itself.^[4]

Is it illegal to browse Tor?

No. CISA, the federal cybersecurity agency, published an advisory with the FBI in 2020 that tells organisations deciding whether to block Tor to weigh the legitimate reasons people use it. Its examples include deployed troops and other overseas voters, who may use Tor as part of voting, and people avoiding advertisers’ tracking.^[2]

What’s illegal offline stays illegal over Tor. EFF’s legal FAQ, which the Tor Project hosts, says Tor isn’t designed or intended for breaking the law, by its users or by the people who run its relays.^[5] The same CISA advisory warns that attackers use Tor to hide hacking.^[2] And each of the federal cases below was a prosecution for bomb threats or for child sexual abuse material.

Can the FBI track Tor?

Tor tries to stop anyone from learning which websites you connect to, but the Tor Project says perfect anonymity is impossible, even with Tor.^[6] US cases show three ways investigators have identified Tor users:

• Personal mistakes (2013). A Harvard student used Tor and a temporary email address to send bomb threats, to get out of a final exam. The FBI found that he had connected to Tor over Harvard’s wireless network in the hours before the threats were sent, and its affidavit says he admitted sending them.^[7]
• Court-approved hacking (2015). After seizing the servers of Playpen, a child-abuse site reachable only through Tor, the FBI got a warrant from a magistrate judge in Virginia to use what it called a network investigative technique (NIT). Code delivered from the site to visitors’ computers sent the FBI their IP address and other identifying details. It identified thousands of computers around the world.^[8]
• Tips from abroad (2019). In a West Virginia case, a foreign law-enforcement agency gave the FBI an IP address that had visited a dark-web child-abuse site. An agent testified that the agency hadn’t told the FBI how it got the address, and in 2025 a federal appeals court upheld the trial judge’s refusal to order more disclosure.^[9]

Appeals courts let the Playpen evidence stand. In 2018 the Fourth Circuit Court of Appeals ruled that even if the NIT warrant was invalid, the evidence could be used because agents had relied on it in good faith, and noted that three other federal appeals courts had reached the same conclusion about the same warrant.^[8]

The rules have since been updated. Since December 2016, Rule 41 of the Federal Rules of Criminal Procedure has let a magistrate judge issue a warrant to search computers remotely, inside or outside the judge’s own district, when their location has been “concealed through technological means”. The official note on the change gives anonymising software as an example.^[10]

Our guide to Tor Browser covers other documented cases, including Silk Road, and what they suggest about staying safe.

Can my internet provider see that I use Tor?

Yes, by default. Tor doesn’t stop someone watching your connection, such as your internet provider or the network at school or work, from learning that you’re using Tor, though it tries to keep the sites you visit hidden.^[6] In the Harvard case, the fact that the student had connected to Tor over the university’s Wi-Fi was part of how the FBI found him.^[7]

If you’d rather your provider didn’t see it, the Tor Project says you can reduce that risk by configuring Tor to use a bridge instead of connecting to the Tor network directly.^[6] The Tor Browser guide explains how bridges work.

Is it legal to run a Tor relay in the US?

Relays are the volunteer-run servers that carry Tor traffic. EFF believes running one, including an exit relay (the last hop, whose address websites see), is legal under US law. It says it isn’t aware of anyone being sued, prosecuted or convicted for running a relay, but that it can’t guarantee you’ll never face legal liability.^[5]

EFF points to two federal laws. Section 230 (47 U.S.C. § 230) gives online services, which EFF says include the Tor network, immunity from many claims over other people’s speech and conduct. A safe harbour in the Digital Millennium Copyright Act, 17 U.S.C. § 512(a), protects against copyright claims over material a service simply passes along. EFF believes relays should qualify, though it notes that no court has yet ruled on this for Tor.^[5]

Its practical guidance is cautious. EFF advises against running an exit relay from home, because police may wrongly attribute the traffic to your household, and suggests a hosting facility, a separate IP address and an internet provider that accepts Tor. It also warns that inspecting the traffic passing through your relay could create liability under state or federal wiretap laws.^[5] It does happen: in 2016, Seattle police mistakenly raided the home of a privacy activist who ran an exit relay.^[5]

Laws differ from country to country. Compare whether Tor is legal in the UK and in Germany, or see our country-by-country guide. If you’ll use Tor on a phone, start with Tor on iPhone and Android.