I can't not believe people are still asking this question. Let me answer the question so I can (hopefully) stop the question from spreading here.
Okay, first of all, using other a rom or ISO is NOT pirating. Huge difference.
How it's different:
Spoiler warning:
Besides, downloading a rom or an ISO isn't pirating, because if it were, Emuparadise would've been sued for lots of money, just like TPB. It's technically stealing, but what doesn't make Emuparadise meet these criterias is that the performance of an emulator is HORRIBLE with any games past 3,000,000 kbs. Try Final Fantasy. Do you know how much money that game made, and do you know how big the game is? Chances are it's either 3,000,000 kbs or past that. Driver: Parallel Lines is 3,000,000 kbs. I ran it on PCSX2 and the textures were mutilated.
Preformance is what makes gamers buy a game. Good ol' try-before-you-buy. (Don't always use an emulator to test performance. This is why YouTube exists.)
EDIT: This post goes just for North American laws.