I don't think there is any law the stipulated what you can and can not download. Such a law would require you to know the statues of all copy rights of all material which is above and beyond reasonable. I do believe that all laws, at least those that have any hope of standing up in court deal with the distribution of copyrighted work. It is very very illegal to distribute copyrighted material to anyone, be it in the park or on the net, however should someone give you such material I do not believe you have any legal obligation to validate the statues of such materials copyright prior to using it for your own personal use. So, obviousness it is a big world and this topic is stupid sense there are a thousand different possibilities, but don't distribute copyrighted material and your will be fine. And with that said, never question the status of copyrighted work, ignorance is bliss. If a copy of this or that falls from the sky, it is not your responsibility to verify anything.
Of course that moral plausible deniability only works if you don't ask yourself stupid questions, like is it illegal for me to download this thing the was uploaded by someone illegally? Keep in mind that most of this shit is add supported, so they very well may nail you for financial support of terrorist organizations. Your best bet is to get your news form usenet, no google adds there. Stay safe, don't fund pirating terrorists.
illegal = distribution of copyrighted material
illegal = bypassing, circumvention encryption
Use of such illegally distributed works is not well defined.
Hacking your wii violets many laws in many countries, hacking your wii to play homebrew is likely much more illegal than downloading this or that.
Depending on your country, if is very likely that fair use backups of legally owned material may be hosted and provided to owners of such material to facilitate there backup needs, aka roms which you and I can not make but joe can. It is legal for Joe to host such backups and provided them to use, so long as we legally own such copyrighted material. Also, Joe may or may not be responsible for any need to validate such ownership, a simple statement from the user may to good enough.
IOS, System menu wads, clearly anyone owning a wii has a fair use right to have these, so possession of them is not illegal. However, depending on your country of origin, distribution of such wads may or may not be illegal.
Forums- for a site to stay up they must ad-hear to the laws of the country in which there server is located. Forms may express rules that are above and beyond any well defined law in an attempt to shield itself from litigation. AKA, the forum does not have the money form any lawyer, legal or not, so don't tell the forum when you piss in the shower, they don't want to know what you did with your sister (in-law?), they just don't need to know.
PS. you can pm me all the details about your sister, just leave yourself out of it.