Copyright law (and therefore DRM, the software companies can use to lock down their products) is controlled by the Library of Congress. Every three years, the Librarian makes decisions on certain critical exemptions. This time around, it looks like they’ve got things right.
The rules specifically cover Section 1201 of the Digital Millennium Copyright Act, which governs fair-use exemptions from all sorts of things. You might be familiar with DRM from MP3s and movies, but it’s far wider-reaching.
Today’s exemptions mean that you can legally access the software in your car, to repair or tinker; jailbreak the smartphone you bought; run a multiplayer service for an old, out-of-support video game; and rip DVDs to make fair-use remixes.