Suppose that Mark Zuckerberg personally favors whichever candidate you don’t like. He arranges for a voting prompt to appear within the newsfeeds of tens of millions of active Facebook users—but unlike in the 2010 experiment, the group that will not receive the message is not chosen at random. Rather, Zuckerberg makes use of the fact that Facebook “likes” can predict political views and party affiliation, even beyond the many users who proudly advertise those affiliations directly. With that knowledge, our hypothetical Zuck chooses not to spice the feeds of users unsympathetic to his views. Such machinations then flip the outcome of our hypothetical election. Should the law constrain this kind of behavior?
"Overall, users notified of their friends’ voting were 0.39 percent more likely to vote than those in the control group, and any resulting decisions to cast a ballot also appeared to ripple to the behavior of close Facebook friends, even if those people hadn’t received the original message. That small increase in turnout rates amounted to a lot of new votes. The researchers concluded that their Facebook graphic directly mobilized 60,000 voters, and, thanks to the ripple effect, ultimately caused an additional 340,000 votes to be cast that day. As they point out, George W. Bush won Florida, and thus the presidency, by 537 votes—fewer than 0.01 percent of the votes cast in that state."