This is the fundamental difference between common law and civil law and is how most legal systems outside of former British colonies work. Common law is a more

This is the fundamental difference between common law and civil law and is how most legal systems outside of former British colonies work. Common law is a more conservative approach in many ways, because laws are seen not as coming from some abstract, idealized system designed years and years ago, but strongly informed by the history of the law as lived through the people subject to it. For example, take the 4th amendment. We're protected from "unreasonable searches and seizures." If you're pulled over for an arrest, does a police officer have the right to search your car? Your glovebox? Your trunk? How about your cellphone? Is the answer, "No, unless Congress passess a law?" Is it, "No, even if Congress passes a law?" If the latter, how do we know and when? What if judges disagree? That's not even to point out that "unreasonable" not only varies between individuals but across time. John Adams didn't think the Alien and Sedition Acts were unconstitutional, for example, though Thomas Jefferson surely did. And what would be considered "unreasonable" to them might be wholly reasonable to us, or vice versa. Congress or other legislative bodies are free to pass laws that specify intent, BTW. They're just awful at it. Really awful. So awful that the same Congress might pass two laws with obviously contradictory intent. Or pass laws which are deliberately open to multiple interpretations for the sake of getting a bill passed more quickly.