We're a few decades into the internet now. One of the most interesting questions to me about the internet is how jurisdictions work. Since the internet is a sort of 'overlay' on the physical world, do borders extend into the overlay, or are they ignored? There isn't a checkpoint or customs like there is when you land in another country and need to present paperwork. So how do we determine what jurisdiction a site can be sued in?

This ruling brings us one step closer to being able to figure it out, and I think it brings us closer to the maybe-naive answer: the jurisdiction is determined by where the servers are. Now, it doesn't go that far, or even really mention servers. But it does seem to conclude that just because a site is visible in a place does not mean the site can be sued there.

Very brief background: a citizen of Texas wants to sue the Huffington Post for libel. But before that can proceed, the court needs to figure out if Texas is the right place for the trial. Eric Goldman's writeup is worth the full read, but in short, the majority finds that simply because a website is accessible to people in a given jurisdiction (in this case, Texas), and even if that website advertises to people in that jurisdiction, it does not mean the website can be sued in that jurisdiction. This approach seems reasonable to me, though it really seems to only apply to sites hosting speech, like blogs or news. There is some language in the majority opinion that suggests if the site had more firm ties to Texas, they might have found differently:

...but its story about Johnson has no ties to Texas. The story does not mention Texas. It recounts a meeting that took place outside Texas, and it used no Texan sources.

But at least in the case of speech otherwise not tied to a particular jurisdiction, I think this ruling makes a ton of sense; I'm not even sure how one would implement the dissenting opinion, which Eric summarizes:

So the dissent apparently is fine with HuffPost being sued anywhere it's geolocating ads, which is likely everywhere. In other words, the dissent would honor the plaintiff's choice of forum. I think the majority reaches the better result.

I agree!

Fifth Circuit Issues an Important Online Jurisdiction Ruling - Johnson v. HuffPost