p2p networking

ok not sure if this is random or ordered so ill put it here.

I wanna know if anyone knows the specific legalities of downloading files from services such as Emule and Kazaa.

I have both of them and i assume they are legal , but i do not understand how ?
Many of them have pirated and illegal copies (not that i care particularly) but im intrigued to know how these are allowed to exist when they flagrantly abuse copyright laws ??
or am i missing some legal loophole…?