_Emualtion_ is 100% perfectly legal _everywhere_.
"Emulation" is nothing more than running a virtual machine, which is one of the cornerstones of computer science. (ie: Heck, look at Java, which is just as much an emualtor as a SNES emu.)
The only real issues ever are patents (not reallty a big deal for emulation except certain machines), DMCA (in the US and some countries, circumvention of encryption can get you into hot water, and some few games are encrypted.), and piracy - BIOS, ROMS, disks, etc.
So _emulation_ is 100% legal and always will be. But if you have to go torrent down a ROM, then _that_ is piracy. If you own the cart, its still piracy -- someone illegally shared the rOM with you, and you went and got it illegally; if you rip your own ROM, thats up to your local laws and I've no time to detail it ehre today
There are many legal methods to obtain ROMs -- ripping yourself, getting them from CDs you bought such as legal sony Atari emualtor discs for PSX etc, the GB Player cards you used to be able to buy, and many other ways.
In _practice_, if you own a cart, and download it online, no one is going to come after you, but its like crossing the street against a red light as a pedestrian; illegal, buit no one gives a crap. Its _uploading_ that is really crossing the line, or _selling_ which is _seriouly_ crossing the line.
jeff