An explainer from Eva Galperin at the Electronic Frontier Foundation on Twitter's "country-based tweet takedown" news.
The key point here, which has been missing in much of the initial coverage, is that the policy announcement is specifically related to the company's global expansion: Twitter is opening offices in more countries around the world. A US-based company doesn't "have to" censor speech according to any other country's laws, but the scenario is quite different for a company opening offices and placing employees within foreign borders. Snip:
Until now, when Twitter has taken down content, it has had to do so globally. So for example, if Twitter had received a court order to take down a tweet that is defamatory to Ataturk--which is illegal under Turkish law--the only way it could comply would be to take it down for everybody. Now Twitter has the capability to take down the tweet for people with IP addresses that indicate that they are in Turkey and leave it up everywhere else. Right now, we can expect Twitter to comply with court orders from countries where they have offices and employees, a list that includes the United Kingdom, Ireland, Japan, and soon Germany.
Twitter's increasing need to remove content comes as a byproduct of its growth into new countries, with different laws that they must follow or risk that their local employees will be arrested or held in contempt, or similar sanctions. By opening offices and moving employees into other countries, Twitter increases the risks to its commitment to freedom of expression. Like all companies (and all people) Twitter is bound by the laws of the countries in which it operates, which results both in more laws to comply with and also laws that inevitably contradict one another. Twitter could have reduced its need to be the instrument of government censorship by keeping its assets and personnel within the borders of the United States, where legal protections exist like CDA 230 and the DMCA safe harbors (which do require takedowns but also give a path, albeit a lousy one, for republication).