They can't stop a good implementation from working (let's not argue about what constitutes a good implementation), but they can force companies to use poor implementations
They can force you to divulge your private key (c.f. UK)
They can force companies to do the same
And if that's the case, come on, a firmware update at the end of the factory line wouldn't be hard to legislate
Or at least, that is what I see happening right now. I don't give two shits if you, personally, can encrypt your email to your mates; the LEGALISED widespread eavesdropping on the general public is the danger, and that most definitely must be fought against.
I'm genuinely surprised. Hello Wyden, you have my attention. Now, where can I get one of these for Parliment?