Twitter’s decision to enable country-level blocking of tweets is a rational response to an Internet that long ago ceased to be that utopian place beyond location. Companies who want to grow global amid the forked legal code of today’s Internet need to follow in Twitter’s footsteps.

It would be great if there were companies that did not want to grow global, who could offer a fortified service from a free speech haven and pay no attention to the thin-skinned legal codes of the world. Such an mission would be difficult to sustain, however: Twitter is not some abstract concept; it costs money to run. Free services need advertising-generated revenue; ads require local sales teams and/or local payment systems. This means local offices, and these are within reach of local laws. A Twitter service used by the world but not paid for by the world is unsustainable. (A hypothetical premium Twitter would have the same achilles heel: local payment systems.)

In terms of fine-tuning its censorship, Twitter is catching up to Google. Google has long had the ability to censor search results on a per-country basis. It also serves mutually exclusive map datasets to India and China, where it is illegal to publish country borders at odds with the official stance. Google does this because it is heavily invested in both countries — not just with sales teams, but with development teams too. Executives face real-world criminal charges for non-compliance, as Google found out in Italy.

A highly relevant question now is: Where should the limits of tolerance lie for Facebook, Twitter and Google when it comes to censorship? When does a country, in Twitter’s own words, “differ so much from our ideas that we will not be able to exist there.”? Let’s say we’re even understanding about Germany censoring Google search for Nazi propaganda and France for Nazi memorabilia. What about the case last week of the Indonesian who posted to Facebook that he did not believe in God, and was arrested for it? Should Facebook remove the post globally? Should it remove it only in Indonesia (something it cannot currently do)? I’d say no in both cases, but many Indonesians apparently prefer not to be confronted with expressions of non-belief in their midst. (The BBC reports the page in question has been taken down, but the group still seems to be up when visited from Sweden. Facebook is able to make entire pages unavailable to specific countries.)

Is this really a fight Facebook should fight alone? Should it be YouTube’s fight to serve videos deemed insulting to Ataturk in Turkey? If we demand Facebook and Twitter and Google exit these markets rather than collaborate with laws odious to our free-speech sensibilities, shouldn’t we demand that other businesses boycott the country in solidarity? And is that really feasible?

When to tolerate censorship, then? It depends. It depends on whether a country is on a trajectory towards more free speech. It depends on whether the local laws in question are created through a broad participatory process that gives them legitimacy. It depends on whether the content objected to is an expression of a fundamental human right, such as a sincerely held belief. More cynically, it depends on whether the company in question has business interests there, chasing a growing user base. (For Google in China, this complex calculation turned against collaboration when it became obvious speech was becoming less free, not more, despite its presence.)

Today’s announcement is a bid by Twitter to ensure that excessive censorship in one jurisdiction does not bleed over into other jurisdictions. In tandem with Google, this approach amounts to a new balance of power between national jurisdictions and the web’s native interest communities. We cannot assume it is a stable equilibrium, however. One risk is that the offer of country-level content blockage is not enough for a censorious regime. It may demand that content be removed globally, else face local legal jeopardy. This is not far-fetched — demands for the removal of military “secrets” from Google Earth make no sense if they can still be seen by everyone except those within a jurisdiction. (So far, with one exception, Google has resisted such requests. China certainly tried.) It is also illegal for Google to post any information about China’s censorship requests globally, as explained in its transparency report:

Another risk is that the outsourcing of censored tweets to chillingeffects.org is only a temporary solution in a long jurisdictional arms race. Censored tweets are currently listed on chillingeffects.org/twitter, where the offending tweet can be read in full, with link and all, thus:

Since Twitter promises to alert us anytime a tweet is blocked, the Streisand effect will likely ensure wide exposure for all content that ends up there. But SOPA and PIPA were phrased to criminalize precisely this kind of “enabling” of piracy by linking, with an added extra-jurisdictional twist: Companies with a US presence would not only be enjoined from directly linking to illegal content, they would also be enjoined from doing business with non-US companies linking to it. I fear non-US legal codes will innovate to mirror this extra-judicial demand, not just for copyrighted material but for all content deemed not in the national interest. China already does (see Google’s transparency report, above).

Finally, one interesting issue I’ve not seen explained by Twitter: The mechanics of this censorship. It sounds as if there will be a block list of links for each country. I assume that once a country demands a link be put on the list, all tweets containing that link will not be shown to Twitter users in that country. But what about tweets that do not contain a link but which merely contain speech objectionable to censors? Will there be a continuously updated list of blocked terms, as is done with Chinese microblogging tools? Or will each individual offending tweet need to be flagged by censors? If it’s the latter, then there is little worry, as the half-life of a tweet is far shorter than a censor’s reaction time. But that is why China sets its own far more onerous rules for those who want to play there.

What if a country with a conservative culture or oppressive regime does demand a list of blocked terms, ostensibly to prevent obscene or defamatory speech? I suspect (and hope) Twitter decides such countries “differ so much from our ideas that we will not be able to exist there.” Twitter could then serve a full uncensored feed to users in, say, Saudi Arabia or UAE or Pakistan; the onus would be on these countries to decide if they want to invest in unilateral blocking technology of the kind China uses for its Great Firewall. That is indeed the route Iran and Vietnam have taken, and which others may yet take as Internet censorship technology gets cheaper and easier to deploy. When that kind of Internet has broadly arrived, we’ll be in the next phase in the Internet censorship arms race.