Is Twitter more like a phone company or more like a newspaper? It's a laughably strained comparison — Twitter is Twitter, not some relic of a previous era — but the answer is central to understanding the pressures on large internet service providers to regulate what their users say. And as more and more speech takes place on the internet, the answer becomes more and more important: the future of free speech might have more to do with corporate censorship than the First Amendment.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.

The First Amendment is one of our country's most cherished institutions — and one of its most profoundly misunderstood. The confusion comes from those first five words: "Congress shall make no law." Congress isn't allowed to abridge your freedom of speech. That means the First Amendment only applies to the government, not private parties — as every kid eventually learns, your parents certainly don't have to respect your right to free speech. "Most first-year law students don't understand this point," says Geoffrey Stone, a constitutional law professor at the University of Chicago Law School. "They think their employer can't fire them because they criticized the president, and they're wrong."

Apple can pre-screen and delete data from your iCloud account if it finds anything 'objectionable.'

That also means that the First Amendment doesn't apply to Twitter or Facebook or Tumblr or any other private messaging platform. Twitter can delete whatever it wants, whenever it wants; no one raises an eyebrow when the service deals aggressively with spammers. Using iCloud? Apple explicitly reserves the right to pre-screen and delete data from your account "at any time" if it finds anything "objectionable." Google and Microsoft have similar policies. Hate speech laws are debated internationally and generally unconstitutional in the United States, but Facebook's terms of service simply say "You may not post content that is hate speech." And pornography, history's free speech flashpoint, is flatly prohibited without definition on every major service. We do not, as Justice Potter Stewart would say, know it when we see it; we are simply not allowed to see it.

(Lest you think The Verge is perfect, note that Vox Media's terms of use track the industry standard: you may not use our comments or forums to post "objectionable" material, and our moderators operate with a strong hand.)

"The top decision maker at YouTube has more censorship power than any Supreme Court justice."

So we're living in a period of uneasy truce: people around the world are sharing their voices on the internet like never before in history, but they're doing so under private censorship regimes equally unique in time. There is more speech than ever under more potentially unchecked control than ever. It is "a double-edged sword," says Electronic Frontier Foundation attorney Trevor Timm, with large corporations both enabling and controlling the ability for average people to reach a much larger audience than previously possible. "The top decision maker at YouTube has more censorship power than any Supreme Court justice," he says. "We have to develop policies that better protect free speech from not only government interference but also corporate censorship."

That's where the phone company / newspaper distinction comes in. The phone company is a "common carrier" in legal parlance — it treats all customers equally, and (hopefully) doesn't monitor what they say or do. Because phone companies doesn't exercise control over what's said on its network, we don't hold them liable for what they transmit. "If the phone company was responsible for every lie ever told on their system, they would have to go out of business," says Chicago's Stone. On the other hand, the newspaper exercises complete control over what it publishes; you can't just ring up The New York Times and have an op-ed published. That control means that the Times is liable for its contents, because it selected them — it can get sued if it prints something false or defamatory.

"The more Twitter regulates, the more it's going to be subject to regulation."

So where do Twitter and Facebook fall? Are they merely transmitting messages and thus free from liability, like the phone company? Or do they bear added responsibility for what their users say because they explicitly reserve the right to exercise control over that speech? Or are they a new thing altogether — and if so, where should we draw the lines for our new de facto public spaces? It's in their best interests to exist in the middle, says Stone. "The more Twitter regulates, the more it's going to be subject to regulation."

The issue is confusing even to our nation's lawmakers. Two weeks ago, seven House Republicans wrote a letter asking the FBI to shut down Hamas' Twitter account after it began tweeting propaganda during its latest skirmish with Israel. (Israel's IDF tweeted right back, of course.) "Allowing foreign terrorist organizations like Hamas to operate on Twitter is enabling the enemy," Rep. Ted Poe (R-Texas) told The Hill. "The FBI and Twitter must recognize sooner rather than later that social media is a tool for the terrorists."

"I think they know nothing of the First Amendment."

It was a strong message, but legally meaningless — Congress is simply prohibited from telling Twitter what it can and can't publish. "I think they know nothing of the First Amendment," says Stone of the letter. "They're playing to constituents." It doesn't matter that Hamas is a foreign group speaking using a US company's platform; Stone says the notion of controlling foreign speech "has long been discredited." The EFF's Timm naturally agrees, saying it would be "completely inappropriate" for the FBI and Congress to get involved. "It's kind of counterproductive for these Congressmen to even be doing this," he says, noting that "only journalists and intelligence agencies" were following terrorist group Al-Shabaab's Twitter account before a similar controversy last year. "By drawing attention to them they're getting a bigger platform."

There are some limits, however — it's not likely that Hamas would ever be allowed to buy a promoted tweet or trending topic, since the Treasury Department prohibits transactions with enemies of the United States. And while Twitter finds it easy to stand up to Congress on free speech issues, it has capitulated to its business interests: it suspended journalist Guy Adams' account after he repeatedly criticized Twitter partner NBC's Olympics coverage and posted the public email address of an NBC executive. And when Twitter was asked to hand over tweets from an arrested Occupy Wall Street protestor, it fought until the last minute — until it seemed as though it would have to reveal confidential financial data to the judge so a fine for noncompliance could be calculated. Then the tweets were indeed turned over, albeit in a sealed envelope ahead of appeal.

"Twitter is the best of the large services."

The resulting backlash over the Adams affair and the general discomfort about the Occupy situation highlight perhaps the only real check on Twitter's ability to control its users: the users themselves. All of our lingering confusion over the First Amendment means the market for these services speaks very strongly when those values appear to be infringed, even if Twitter has the right to do whatever it wants. "I think it's a welcome idea for Twitter to say that it chooses to take First Amendment values seriously," says Harvard Law School professor Jonathan Zittrain. "We don't tell people they can't speak because of the political content of their views." The EFF's Timm agrees, noting that "Twitter is the best of the large services. They try to stay true to the First Amendment as much as possible."

And while that may change over time — Twitter and Facebook can certainly tweak the rules whenever they want — Chicago's Stone thinks the market will keep things in line. "There are a lot of platforms," he says. "I am not concerned about one platform doing something. If people don't like one, they can go to another."

Just make sure you read the terms of service.