When I leave a friend on my laptop. As the owner of the laptop, am I liable if he does something illegal?
In what way?
Rather no. But the device ID is often sent along with it.
BUT- if he doesn't do the illegal thing over your internet connection, nothing should happen to you.
If he does something illegal on the Internet via your line, then you are liable as the subscriber. It's logical…
Read the other answers.
What about it? It always depends on how illegal it is…