From Edward Felten’s "DRM and the Regulatory Ratchet":
Regular readers know that one of my running themes is the harm caused when policy makers don’t engage with technical realities. One of the most striking examples of this has to do with DRM (or copy-restriction) technologies. Independent technical experts agree almost universally that DRM is utterly unable to prevent the leakage of copyrighted material onto file sharing networks. And yet many policy-makers act as if DRM is the solution to the file-sharing problem.
The result is a kind of regulatory ratchet effect. When DRM seems not to be working, perhaps it can be rescued by imposing a few regulations on technology (think: DMCA). When somehow, despite the new regulations, DRM still isn’t working, perhaps what is needed is a few more regulations to backstop it further (think: broadcast flag). When even these expanded regulations prove insufficient, the answer is yet another layer of regulations (think: consensus watermark). The level of regulation ratchets up higher and higher – but DRM still doesn’t work.
The advocates of regulation argue at each point that just one more level of regulation will solve the problem. In a rational world, the fact that they were wrong last time would be reason to doubt them this time. But if you simply take on faith that DRM can prevent infringement, the failure of each step becomes, perversely, evidence that the next step is needed. And so the ratchet clicks along, restricting technical progress more and more, while copyright infringement goes on unabated.