Defeating Draconian laws
There's due process, which is the route CAGE is taking, but I'm not hopeful. A rational and humanitarian regime would not have introduced such Draconian legislation to begin with. Reversing it will require nothing short of replacing the very foundations of our extremist political system. Good luck with that.
Meanwhile, Rabbani and others can save themselves a lot of hassle by using more clandestine methods to protect their privacy.
It turns out that the old cliché about "security through obscurity" is sadly wrong, given the "rubber hose decryption" era we now live in. Certainly if obscurity is the only layer of "security" then it patently isn't secure, but it is now an essential layer nonetheless.
Encryption is no longer sufficient. Now you also need to hide the encryption. In this scenario I'd recommend whole disk encryption with a hidden volume, with the outer volume containing a "dummy" OS suitably seeded with innocuous data, and the "real" (hidden) inner volume containing the real OS and data.
The upshot is that when Plod (or more likely these days some private contractor with a badge and a gun) demands your password, you happily give it to him, and he decrypts and views a whole bag of nothing (substantial), but it's a sufficiently believable bag of nothing that he doesn't even go looking for the real contents, has no way to prove that a hidden container even exists, and would have no way of decrypting it even if he suspects he might be looking at one.
No it doesn't address the underlying political issue, but in these dark times it's probably the best you can hope for.