Well unfortunately you don't get off the hook simply by saying that it wasn't you, you have to prove it wasn't you and if you do, you still get fined because you neglected the security of your network installation.
To "help" people with securing their network, the french government issued a 200+ pages specification for a software that would secure your computer and prevent it from being used to downlaod illegal content.
The specification requires the program to be one the best malware ever created, able to disrupt anti virus and anti spyware so it's not removed by error, hidden so the process can't be killed by the user, so the program can't be uninstalled, logs in both a crypted and an unencrypted files all network actions of the machine, etc etc
Basically the best spyware ever. This is on the market for a contractor to realize. Oh and obviously people will have to buy it to comply with the network security requirements.
I cant' wait for the first lawsuits.