Say that Congress passes a statute banning the public distribution of files that, when submitted to a 3D printer, will produce a set of parts that could easily be assembled into a gun. (Assume that this is defined precisely enough.) Would this violate the First Amendment? (This is obviously related to the cases involving Defense Distributed and Cody Wilson, but it avoids some of the procedural complexities of that case.)
I think this is an interesting, unsettled, and conceptually difficult question, which of course can apply to regulations of many kinds of computer instructions, and not just 3-D-printer gunmaking instructions. And one way to see the complexity is by considering two analogies and one near-future hypothetical:
[1.] Software is like hardware: Imagine that I build a hardware device that, when attached to a 3D printer (or to some other such device), will cause the parts to a gun to be produced. It's a physical object, not a set of computer files, but it has the same effect: It causes the same parts to be produced. It's pretty clear that, whatever the policy or moral merits of banning distribution of this hardware device might be, there's not a First Amendment problem with that.
Now the 3D gun design files can be viewed and understood by technically savvy observers; they aren't just machine code, but contain visual images and (more or less) source code of a sort. Such fellow engineers can learn from the designs, can spot flaws in them, can figure out how to improve on them, and can better understand how even very different objects can be 3D-printed.
But the same is true about my hypothetical hardware device. Engineers can learn from physical objects just as they can from computer code and from blueprints. They can look at the object, take it apart, fiddle with it, figure out its flaws, understand how to improve it, and better understand engineering more generally.)
The government can still restrict the device despite its possible communicative qualities, when the restriction is imposed because of what the device does, not because of what it communicates to human observers. If the government wanted to ban physical objects with electronics and moving parts when they contained (or displayed) pictures of Mohammed, or of a burning flag, or of white people in blackface, that would violate the First Amendment because the restriction is applied because of what the physical objects communicate to people. But if the government bans physical objects because of the potentially dangerous things they can be used to do (fire surface-to-air missiles, create guns when attached to 3-D printers, and so on), that's generally not a First Amendment violation, even though it does incidentally affect engineers' ability to communicate with each other by passing around such objects. (I oversimplify here, but that's a good first cut.)
This roughly tracks, by the way, the distinction between content-based laws, which are generally laws that restrict speech or expressive conduct because of what it communicates to humans, and content-neutral laws, which restrict speech because of effects that exist entirely apart from such communication. Indeed, some court cases have held that restrictions on publishing computer source code are speech restrictions, but suggested that they might be content-neutral ones rather than content-based ones.
And, if that's true for the hardware, why should First Amendment law distinguish hardware from software? If there is no First Amendment problem with banning distribution of physical devices that, when attached to a 3D printer, produce gun parts (or anything else that the law might specify), why would there be a First Amendment problem with banning distribution of computer files that, when uploaded to a 3D printer, produce gun parts?
[2.] Software is like an instruction manual: On the other hand, consider (I'm just picking one book of an Amazon search), Gunsmithing at Home: Lock, Stock & Barrel—A Complete Step-by-Step Fully Illustrated Guide to the Art of Gunsmithing. Say the government tries to ban it, because of a worry that people will use it to make guns.
This ban would clearly violate the First Amendment to the extent that home gunsmithing is itself legal. But even if home gunsmithing were banned, banning the book would raise very serious First Amendment problems, and would likely be unconstitutional. Such a ban would certainly be treated as a content-based speech restriction, and subject to very demanding First Amendment scrutiny. And this is so even if the government argues that it's banning the book simply because of what people can physically do with the information they learn.
Now I think First Amendment law can meaningfully distinguish actions that cause harms as a result of communication to humans from actions that cause the same harms through noncommunicative means. If I cause customers to avoid your business because I physically block the entrance (or, say, set off a stink-bomb right next to it), you can sue me for your lost profits (and more). If I cause customers to avoid your business because I express critical opinions about your business—or because I publicly criticize any customers who visit your business (see NAACP v. Claiborne Hardware Co. (1982))—your suit would be blocked by the First Amendment.
Likewise, the government can restrict the distribution of precursor chemicals that can help people engage in drug making or bomb making, but the First Amendment seriously constrains the government's ability to restrict the distribution of chemistry textbooks that can also help people engage in drug making or bomb making. (See my Crime-Facilitating Speech article for much more on that.) Thus, while helping create guns by communicating knowledge to humans is protected by the First Amendment, helping create guns by creating mechanisms (hardware or software) that can be used to create guns might not be as protected.
At the same time, I've got to admit that this distinction is pretty conceptual, and many might see it as gossamer. Certainly some judges seem to view the gun-3D-printing files as similar to books, though other judges uphold restrictions on such files that they likely wouldn't on books.
[3.] Alexa, read this book and make me a gun: Finally, let's imagine a technology that we don't yet have, but might have in a few decades—a 3D printer that can follow technical instructions written in English. You give it a link to a simple version of Gunsmithing at Home, give it the right command ("follow the instructions on pages 31 to 37"), and it makes a gun, just as it can make anything else.
If the government can ban 3D-printer files that could be used to create gun parts today (perhaps because courts accept analogy 1), does it mean that it will be able to ban Gunsmithing at Home then? Conversely, if we think the First Amendment would still prevent the government from banning Gunsmithing at Home in my 3D-printer-that-understands-English hypo, does it mean that the First Amendment today prevents the government from banning the specialized gun-3D-printing files?
One possible answer might be:
[A.] A ban on specialized gun-3D-printing files today would leave open ample alternative channels for humans to explain how guns are made through ordinary English text (even if that text would not convey precisely the data that a modern 3D printer would use to make gun parts), and is therefore constitutional.
[B.] A ban on Gunsmithing at Home would not leave open such channels, since any book about how guns are made would (by hypothesis) be potentially usable by the super-smart 3D printer; it is therefore unconstitutional.
(Under First Amendment law, a content-neutral restriction—and recall that analogy 1 argues that a ban on gun-3D-printing files is content-neutral because it focuses on what the files do, not what they communicate to humans—is often constitutional, but only if it leaves ample alternative channels for conveying the underlying information or ideas.)
But perhaps this also is too gossamer and conceptual a distinction, especially when protection of the right to publish books about human knowledge and technology is at stake.
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There is of course a lot more to the Defense Distributed / Cody Wilson debate. There are federal administrative procedure questions raised by the recent temporary restraining order entered against the Trump Administration. There are federalism questions raised by states' attempts to use state law to restrict what Defense Distributed can post on the Internet in other states. There are possible Second Amendment questions. There are practical questions about whether the government can do anything (short of imposing massive nationwide Internet filtering requirements) about the distribution of these files, given how easily they can be posted on other sites, including off-shore sites. There are moral questions about the proper scope of government power. But, as I hope I've shown, the First Amendment questions are thorny enough that they are worth thinking about on their own.
(Many thanks to Kit Walsh of EFF for a very helpful discussion that helped me think more about these issues, especially the English-understanding-3D-printer hypo.)