A lot of Lessig’s thinking in Code can be seen in the way in which the Creative Commons project developed and ultimately went about achieving its goals. Specifically, you can see Lessig’s thinking about hacking, and about the way code affects behavior, in the three-level approach of the Creative Commons project. The way the project defined its three levels to write for (machine, human, legal) is interestingly analogous to writing a given piece of code for three different programming languages or operating systems. In fact, I think the operating systems analogy might be apt here.
With its goal of changing the way that people think about, distribute, and reuse creative works, the Creative Commons had to target multiple levels of society. Interestingly, though, each level needed similar things, but accomplishing those things was vastly different depending on what was being targeted.
The legal system, the code of law (an especially apt turn of phrase in this instance) required a strict and carefully defined set of documents which conformed to the “operating system” of the courts. This code had to be comprehensive, well-planned, and legally unassailable if the project as a whole was to succeed. Errors at this level could easily cause the entire project to collapse as they could lead to the social goals of the project failing due to the lack of legal support. If the project claimed to encourage sharing, but legally did nothing, then it could not possibly succeed.
On the opposite end of the spectrum there was the machine-readable code. Computer code in a literal sense (it actually might be more accurate to talk about it being a code schema rather than actual code). It isn’t entirely clear to me just how make-or-break this was to the project’s success, but it could easily be rather high. The machine-readable part of the project was primarily about reducing the effort of using Creative Commons-licensed work. By marking such work in ways that computers could filter, it made it much easier for people looking for materials to use to find them. This sort of friction reduction often makes the difference between achieving a critical mass of adoption for a big project and it ending up in a niche of people who like the idea and are willing to put up with the tremendous amount of work required to sustain participation.
Finally, there was the human code. Making the Creative Commons project understandable in plain language (with the legal language supporting that plain language understanding) was vital for a number of reasons. It allowed non-lawyers to see what was going on with the project, but more importantly it allowed the project to explain itself. This was vital because at its core the Creative Commons is an attempt to hack the way society thinks. The legal and machine-readable code all exists to support a shift in human thought and behavior patterns, and the code of human society, while supported by both, is neither legal nor machine-readable.
Ultimately the Creative Commons project succeeded to the degree that it did because it combined hacks to all three of these “operating systems”. Hacking any single one of them would have failed because, for instance, changing the legal code without making people care about those changes would have made the project basically inert.