About the law
Laws are documents that describe what you are allowed to do in a particular jurisdiction. They are made by (hopefully democratically elected) legislators, and they're written for humans to interpret. Laws can be very specific on some points, but often also leave certain things vague. Sometimes this is even done on purpose, when the legislators decide that they cannot foresee all the cases that will develop in the future.
In case of some conflict, either between society and some individual or company in it, or between companies or individuals, some interpretation of how the law applies to this specific case has to be made. This is done by a judge. Judges will take into account the text of the law itself, the (recorded) discussions that took place when it was made, and rulings by other judges in similar cases. By doing the latter, they try to keep things consistent and therefore fair.
The collected rulings of earlier cases are together known as case law ("jurisprudentie" in Dutch). Over time, the vague areas in a law are filled in by case law. However, this is a slow process, and it is always incomplete: if the law is vague and there is no case law yet, or no sufficiently similar case, then a gray area remains.
As a result, it often makes more sense to think about legal issues in terms of probabilities and risk, rather than in terms of truth. This means that decisions on how to act given the legal situation always have a policy component to them. How important is what you want to do, and how much risk are you willing to take?
Of course, there is always an ethical side to these kinds of decisions as well: something may be strictly speaking legal, but that doesn't automatically make it the right thing to do. While it may be impossible in some cases to say with absolute certainty whether something we want to do is legal, we should always make sure that it's the right thing to do.