What Jack Dorsey and Sheryl Sandberg Taught Congress and Vice Versa

The candor seemed to work. Even some of the most skeptical lawmakers sounded impressed by Mr. Dorsey’s willingness to engage. Representative Joe L. Barton, a Texas Republican who focused almost entirely on the theory that Twitter was limiting conservative voices, congratulated Mr. Dorsey on his appearance “without subpoena, and sitting there all by yourself — that’s refreshing.”

The regulatory future remains a mystery.

At the heart of these hearings was a perplexing question, one that was rarely addressed: What power does Congress have to regulate how tech companies manage their services?

Under Section 230 of the Communications Decency Act, the 1996 law that governs much of online conduct, tech firms enjoy broad immunity from liability stemming from what users post on their services. There’s general agreement among people in tech that the law has been crucial to the internet’s rise: Because they cannot be sued for defamation or libel for what people put online, companies like Facebook and YouTube were able to achieve planetary scale.

Would it be a good idea, now that these companies are so big and powerful, to limit that kind of immunity? Should Congress try to wrest more control over how these companies manage their services — perhaps to gain transparency and maybe, in the way the Federal Communications Commission once did with television and radio, to ensure some kind of “fairness” in the way they affect political speech?

A few lawmakers broached these ideas on Wednesday, but none wrestled with the central difficulties. Some of the thorniest involve the First Amendment, which prevents the government from dictating or censoring speech. Although tech companies, being private services, are free to limit any speech they want on their networks, it was unclear if Congress has any basis for requiring certain fairness or speech policies from them.

“I just don’t think we’ve begun to wrestle with the deep constitutional issues here,” David Pozen, a constitutional law professor at Columbia Law School, said. He pointed out that tech companies themselves enjoyed a First Amendment right against the government’s imposing rules on their services.

Kate Klonick, a professor at St. John’s University Law School who has extensively studied tech companies’ content policies, said she had consulted with several lawmakers on these questions.

“These are real, serious issues that some of us have been working on for a very long time, and they’ve been stewing and ripening without resolution,” she said. “Maybe you can say, now that people are finally paying attention, that we are maybe stumbling toward some better understanding of what’s involved.”