Twitter's new European boss has suggested that users who break privacy injunctions by posting on the site could face the UK courts.
Tony Wang said people who did "bad things" needed to defend themselves.
He warned that the site would hand over user information to the authorities where they were "legally required".
Lawyers are challenging Twitter in court to reveal the identities of Twitter users who violated a super-injunction.
MP John Hemming named Manchester United footballer Ryan Giggs in Parliament on Monday as the footballer who had used a super-injunction to hide an alleged affair, after Mr Giggs' name had been widely aired on Twitter.