Lets see if I can put that degree to some use for a second:
From what I can remember, uploading copyright material is, as Pittrek says, of course illegal. However, Im pretty sure downloading is also technically illegal, as you have made digital copy of copyrighted material without permission.
Bootlegs still contain elements of copyright, in that the songs being performed are copyrighted, however the sound recording itself is the property of the person who recorded it, and if they have chosen to share/distribute it, they can have no complaints.
Bands in theory could pursue bootleggers, and those who share them, such as we, but I think although techically there is a copyright breach, they would struggle to show much loss, and this would be a massive undertaking and waste of time anyway.
Long story short, bootleg sharing is probably essentially illegal I think, but NO ONE is arsed about it since it goes on amongst hardcore fans who will buy the official live releases etc anyway, so record companies/bands turn a blind eye. Theres little danger of getting in legal trouble with it.
Official releases on the otherhand - well, anyone in Europe or the US who thinks downloading tons of these will be able to continue indefinately will probably get a shock one day soon, and it serves them right. Both p2p users and the guys who set the networks up in the first place and maintain them are targets for the industry right now, and they have the technology and gradually the law in their favour. The rest of the world can only be a matter of time I reckon.