If your friend type some notes to you in Words document and make
it a torrent and you download it, then no police in this world can
sue you!
P2P is legal. What makes it illegal is the type of items you
download. All items without official distribution lisense is
illegal for downloading. For example, someone bought a DVD movie.
He then ripped it out and seed it for other people. This item will
be illegal as its legal distribution lisense is only in the form of
a DVD. Once ripped and largely distributed, it will be against the
law.
In short, anything you want but usually needs to pay for it will be
illegal if you go and download it.
As whether or not you can be traced and caught, very unlikely but
possible
