Remember that widespread "emotional contagion" Facebook study that people are freaking out about (especially if they've seen too many negative posts on their feed)? Now, because of the researchers' ties to the federal government, the study might in fact be illegal.
But as legal scholar James Grimmellmann points out, there's a federal law that prohibits universities from conducting this kind of experiment without explicit, separate consent (none of this burying-consent-in-the-fine-print bullshit). Two of the three researchers who worked on this were working for federally funded universities with institutional review boards, and the project received federal funds.
It's one thing when Facebook does this as a private company (though, in that case, fuck Facebook, still), but on behalf of federally-funded researchers, then no. We'll see, though, if there are actually any such repercussions that arise from this experiment in psychological warfare.