Here's a summary of the legal issues that we should consider:
http://www.eff.org/issues/coders/reverse-engineering-faqNow, regarding other firmware hacks, some manufacturers like them (e.g. Microsoft
Surface and
Kinect; Asus supports
dd-wrt), some are afraid of mass bricking (e.g.
Panasonic), some just refuse warranty (
Rockbox vs Iriver and Archos), some attempt to block the hacks in recent firmware update (e.g.
Samsung vs SamyGO) and the bad ones resort to legal threats (Sony:
PS3,
Aibo; Texas Instruments:
TI-83 calculators).
So far, Canon has not made any statements about Magic Lantern, nor CHDK, to our knowledge.
There is some anectodal evidence that using it
might not even void the warranty (just unofficial statements from some service guys). In Europe you might not lose the warranty at all according to
this post (unless you brick the camera).
There is also a rumour that 1DX might have identical hardware as 1DC, and another rumour that Canon
will consider legal action to anyone who will modify the features of the 1DX. Last week, this got a lot of coverage on blogs/forums (
lwn.net,
nofilmschool,
eoshd,
dvxuser,
potn,
doodleme and others).
Now, since we never considered porting ML on the 1DX (because of high price, small user base and high costs in the case of bricking), this rumour doesn't mean much for us. It's just another reason to stay away from the pro market, and limit ourselves to the low and midrange dslrs.
Of course, we are careful to stay within the legal limits, but that's what we did since ML started. Both USA and EU laws allow us to reverse engineer without requiring permission from Canon, but there are some restrictions (we can RE for achieving interoperability between the camera and our own software, not for stealing features from a more expensive camera).
And yes, this means walking on eggs.
For the original question: I don't think anyone is breaking any laws for installing ML on his camera. It's yours - you bought it, you can void your warranty and do whatever you want with it.
