Do the joints look exactly like regular cigarettes, and did the person put them inside a pack with other regular cigarettes?
The joints could look like the big fatties in a Cheech and Chong movie and be wrapped up in baggy with the word "JOINTS" written on them, but if they were stuffed under the sofa in your living room, your not likely to see them every day. But that won't stop a drug-sniffing dog from finding them during a DEA raid. Just like the illegal mp3 files could be named "PIRATED SONY RECORDS SONG.mp3" or the more innocent looking "innagoddadavida.mp3" and left in a directory you hardly look in. Posession is unlawful and subject to criminal sanction and in this case, civil penalty as well.
I could also claim complete ignorance of the way that the song downloading program works. I could plausibly claim complete ignorance that it was even on my computer. I am blonde, all it would take is a little white-out on my computer screen.
Let me introduce you to a legal phrase, here and now, before you end up trying to use that one: "Ignorance of the law is no excuse." It's not right, it's not fair, but it's the law and judges and lawyers use it every day with great success. And if you are going to use the blonde defense, you better hope you have a male judge and a nice rack...and I don't mean spice rack! ;)
Nobody could claim that they didn't recognize the funny looking pills or joints in their purse.
I've seen a few women in court claim that...just before being found guilty. And not long after them was the girl who's boyfriend stashed a few hits of acid under the seat of her car...she managed to plead trafficing down to posession because she had a nice rack...and I STILL don't mean spice rack.
Barely on-topic, but ignorance of the law is a legal excuse, so long as it can be demonstrated that the government did not make a good-faith effort to make the public aware of the law. However, the threshold for that good-faith effort is so exceedingly low, that it's almost never invoked successfully. Whatever the case, it's impossible to argue that the RIAA hasn't made a good faith effort to make file-sharers aware of copyright law..
You basically hashed over the same things you and I have both already said. I'll make it a little clearer.
Differences:
#1-Drugs are less likely to be carelessly left behind because they cost money. Drugs cost money, and you don't leave money at someone's house very often, do you? Files would of course be left.
#2-Illegal files are not only free, they are non-portable. Even if someone emails or copies the file, the original stays on the computer unless deleted. Drugs are portable and would be expected to go with the person. Files=not.
#3-Everyone is capable of searching the house for drugs. Everyone is not capable of searching their computer.
#4-Drug users are generally easy to spot. Computer file sharers are not so easy. The dark socks worn with shorts may give some of them away, but too many of them look like normal people. ;)
#5-Considering #3 and #4, everyone can be expected to know when someone using drugs has been in their house and should be expected to look for illegal objects, and could reasonably be expected to find them. Everyone could not reasonably be expected to find illegal files.
#6-Everyone found with illegal drugs is not always even suspected of being in possession of those drugs. I've got family in law enforcement and I majored in criminal justice, with quite a lot of contact with those in the force. The gal with the drugs in her car who says the boyfriend did it usually has to show signs of being a drug user or have a large amount of the stuff to get arrested. If they are in her purse, then she knew about them. It's rare for someone to go in a woman's purse without her knowing about it, and even rarer that she would not check her purse and easily see the drugs within a half hour of being out somewhere.
The decision on who to arrest and prosecute is based on the circumstances. If the cops come to your house looking for illegal files, and you've got your shorts and black socks on, I'd recommend getting a good lawyer. If you are a regular Joe or a youngish kid, or especially a (non-horribly-ugly) woman, get the lawyer anyway, but I doubt it will make it to trial.
There are just too many differences in these cases for any competent lawyer to allow most of their clients to get convicted for something like this.
Do you really believe those gals that say their boyfriend put the pot in their purse? You believe they didn't know about it? To get off for something like that, you need a very good and airtight explanation of how something illegal came to be in your possession. If you could prove that your house had been broken in to the week before the cops busted you with a few joints under the couch, AND your house was messy so you can prove you don't clean very often, a good lawyer would make a case that the burglars left their pot behind. You'll have to have a VERY good explanation for why there was pot under the couch. Most people don't, because it was their pot.