Even simple features can have far-reaching effects, like improving voter turnout. As Harvard Law School professor Jonathan Zittrain wrote last year, Facebook could decide an election without anyone knowing it by notifying some users that their friends had voted but not others. While no evidence of “digital gerrymandering” has ever come to light, there’s enough risk to make people keep a close eye on the implementation of Facebook’s efforts to register people to vote and encourage them to participate in the democratic process.

Source: Facebook Study Says Users Control What They See, But Critics Disagree