You aren't the only one, but with Freenet it's fully encrypted. Let's say you had a Freenet Silk Road application. You won't know it's a Silk Road web page that's being saved along with images of marijuana to your computer unless you go through an indexer/search site and even then you still won't know that those bits of data are stored specifically on your machine.
So in order for the cops to know your machine was used to store the drug listings, the cops would have to spy on your machine and crack the encryption of the Freenet protocol and essentially monitor it. This is why undercover work is important to the police. If no one reports you for the crime of buying drugs and no one discovers the drugs in transit, then the police don't know what's happening. The only way to catch mobsters was through some undercover work and hoping that someone in the criminal network would squeal. If one criminal says the other 10 criminals actually had a hand in committing a crime, the police have more to investigate and can build a case.
If you're not buying drugs or selling drugs and the data related to the drug listings is encrypted when stored on your machine and encrypted when served from your machine, you may be unknowingly helping a criminal to buy or sell drugs. But I'm not sure how that's discoverable by the police and I'm not sure how it would be turned into a criminal investigation. By the argument that you're allowing this, then all ISPs and cell providers are in big trouble because they also enable drug dealing.
There are some horror stories for Tor node operators though.