Under the law, there are things known as "legal fictions." These are things that are, by their very nature, known to be untrue, but which are treated as true under the law.
The most basic one you learn in law school, and one that even non-lawyers generally know, is that "ignorance of the law is no excuse." What this really means is that, generally speaking, everyone is assumed to know the law. This comes into play in particular with criminal law, where it is assumed that everyone knows what is illegal and so can be held accountable for violating the law, no matter how obscure. There are exceptions to this. Most basic would be laws that specifically require knowledge. But that is clear in those individual laws.
What makes it a legal fiction is the sheer volume of the law that is out there. Even the most hardened expert has no idea what all of the criminal laws out there are. That in itself I think is a problem that needs to be addressed (for instance, I'd make it a constitutional rule that all criminal statutes expire every year (or some other short period) and have to be individually considered and debated, with full public comment, before they can be renewed. That would help keep the total number of criminal laws low and would also help to make sure they are really relevant.
But back to the fiction. Obviously, no one knows these laws. So it is pure fiction to treat people as if they did. The reason this is done is because, if we recognized the reality of this, it would be too hard to convict for any of the non-obvious crimes (theft, murder, etc would be pretty obviously wrong), and we can't have that. That would weaken the power of the state over individuals. And really, I think that is the point. Every legal fiction I've seen, the common theme seems to be, they are about giving a burden to individuals and power to the government. It never seems to work the other way around. I think that is what bothers me the most about legal fictions.
Another kind of legal fiction is the "fact finding" made by Congress with some laws that actually is contrary to reality. Like with making Marijuana a schedule 1 substance, even though empirically, by the very rules set up for schedule 1 under the law, it is not. Congress got around reality by just declaring it was by passing a law that says it was with "congressional fact-finding." They tried to do the same thing with laws against certain kinds of abortion procedures. In an effort to avoid the constiutional requirement that there be health exceptions for any ban at a certain time, congress wrote into the law "fact-findings" that there were no medically necessary health exceptions for this procedure, ever. Of course, this was a political finding, not a factual one.
If I had my way, the constitution would also ban such bullshit as that and leave factual findings where they belong, with fact-finders, not law-makers. Oh well.
Maybe if I get around to it, I'll explore some other legal fictions.
4 years ago