He planned to teach something about TOR in his class so he started using it himself in order to be able to talk about it more authoritatively. One day the network-security technician and two campus police detectives showed up at his office. They claimed that his use of TOR violated the University's responsible-use policy (though Paul had helped write the policy so he knew it didn't) and asked him to not only stop using it, but also to not cover it in class! To his credit he refused the request on the grounds of academic freedom. He wrote about it in Caught in the Network.