UPDATE 1-Twitter's top legal executive steps down in surprise move
(Adds law professor comments, details, background)
SAN FRANCISCO Aug 30 (Reuters) - Twitter's top lawyer, known as a champion of free speech, unexpectedly stepped down on Friday as the microblogging company moved closer toward a long-expected initial public offering.
Alexander Macgillivray, known for fending off legal challenges to Twitter users' right to express themselves in pithy, 140-character messages, himself tweeted the news without giving a reason for the move.
But Macgillivray, who became Twitter's general counsel in September 2009, said he would continue to support the San Francisco-based company as an adviser.
Twitter declined to comment, but said Macgillivray would be replaced by Vijaya Gadde, who has been managing the company's corporate and international legal work. Gadde is a former senior director in Juniper Networks Inc's legal department.
Gadde has deep experience in corporate and securities law, while Macgillivray's specialty is intellectual property.
Twitter, which has more than 200 million active users, is widely expected to go public in 2014.
Macgillivray, who has been credited with coining the motto that Twitter is the "free speech wing of the free speech party," helped shape Twitter's reputation as a champion for its users' rights over the years.
In 2012, Macgillivray's legal team fought a court order to extract an Occupy Wall Street protester's Twitter posts, and resisted when India's government asked Twitter to take down tweets considered inflammatory.
That same year, he publicly apologized after Twitter briefly suspended the account of a British journalist for posting the work email address of an executive at NBC. The journalist had been openly critical of the network's Olympics coverage, around which Twitter had built a massive marketing initiative.
"I think they're really aware of themselves as being a place for discussion, news and sometimes for dissent," said Ryan Calo, a law professor at the University of Washington, referring to Twitter.
As a result, the company has had a longstanding commitment for free speech and privacy principles, which would not easily be shaken by Macgillivray's departure, he said.
Twitter's public policy group, which previously reported to Macgillivray, will now report directly to Chief Executive Dick Costolo, the company said.
Macgillivray said in his blog post that after four years at Twitter he was looking forward to the change.
"I'm looking forward to engaging my various Internet passions from new and different perspectives, seeing friends and family without distraction, and just goofing off a bit. We should all do more of that," he tweeted. (Reporting by Alexei Oreskovic; Editing by Richard Chang and Lisa Shumaker)