First, an aside -- I'm not talking about the unauthorized duplication of copyrighted materials. I'm talking about extranational, rogue groups that steal things at sea and in the air. Though it's an interesting bit of propaganda that the content cartels have successfully expanded the definition of "piracy" to include the former, introducing a spurious comparison to the truly awful original meaning of the word.
Legal Affairs' July/August 2005 article entitled The Dread Pirate Bin Laden. Apparently, "international law currently lacks a definition of terrorism as a crime" [from the linked article]. And when you really think about it, it's really hard to come up with one; it's almost as if the actions and methods of terrorism are designed to hamper its definition and categorization by the groups (nation-states) that have the matériel to fight them. A response, you might say, to the evolutionary pressure of an internationally accepted legal framework. That social-Darwinist take on the issue points to an interesting question, then -- if the methods of terrorism arose in response to the formalization of inter-state relations, why didn't it arise at the same time that formalization happened (the late 17th century)? Why did it take three hundred years?
What if it didn't?
I'm sure you see where I'm going here. As the linked article states, in rather impressive (to a layman, at least) detail, there are real and valuable and effective parallels to be drawn between terrorism and piracy. Their crimes share methods, aims, and locuses; even their rhetoric can be compared -- as can the rhetoric of nation-states that are/were affected by them. Perpetrators and victims. I wouldn't be surprised if the laws governing terrorism, when they arise, look very similar to the ones governing piracy. Of course, there are some differences between terrorism-by-piracy and terrorism-by-suicide-attack that are worth mentioning. The latter are harder to spot and probably more ideologically driven than their economically-driven forebears. But ultimately, they're close enough for at least some of the precedent to apply.