After six hours in front of the House Energy and Commerce Committee, Mr. Zuckerberg is finally finished testifying on Capitol Hill.

By and large, he fended off the tough questions from Democratic lawmakers about foreign election meddling and Cambridge Analytica, avoiding major blunders or pitfalls. Conservative lawmakers pressed the Facebook chief over censorship and alleged bias.

It remains to be see what kind of action Congress might take. Both Republicans and Democrats expressed concerns about the privacy rights of Americans online but expressed different ideas about how best to regulate them.