I often saw many laws in various countries were adopted because various premises, like religious, national (which in mostly are not national, but those the one want to be national) or simply they refer to such vague things like "moral fall" and other similar stuff. Such explanations sometimes are given by legislative bodies, not random people on the net.
I never argued with actual legislator for a start. What goes next goes for random people on the net and real life.
I often saw other kind of arguments, which seem to be a little bit better than listed. E.g. they are believed to be beneficial for society. For example, the argument for porn restriction often is that teenagers' brains are still in development. At the same time, this argument seems strange at least, because people usually do not provide any links for studies.
There are other "arguments" (claiming they give unreal expectations, for example), which I would rather call actual porn criticisms than arguments for categorically prohibiting porn for non-adults. But I won't take faulty generalizations in the scope of this question.
And this was a single example, there are other laws covering other life affairs. And many justifications are based on "facts" which are not supported by links to studies.
It does not mean, of course, such studies do not exist. But probably even arguers are not aware of them (otherwise they would provide me links). But do legislators commonly (means significant part of them do so) at least sometimes take any premise without links to scientific studies? Or is this rare occasion? I am in particular interested in western world.
The question asks if lawmakers use scientific method in order to achieve their political goals (which always will be to some degree subjective) or if they use unscientific method.