The law requires a different kind of approach than what we call "science". There are a number of reasons, but the most important ones are that:
 - legal rules project into the future, and are purpose based (they aim to achieve a goal)
 - legal rules try to make the correct abstractions that will cover the appropriate scenarios in the future in order to get to that purpose
 - legal rules have a profoundly different feedback loop system than "scientific" laws. You are allowed to break legal rules (e.g. your car does not actually have a speed limit - the law has one; and the ability to break it makes it a "legal" rule, rather than e.g. a software algorithm), and that ability to break them is a fundamental feature, not a bug. Challenging laws in the courts is part of the essence of a rule of law based system of laws. this is related to the fundamental inability to know the future, and know if all scenario's are properly covered.

Finally, the law also aims to achieve or enhance "justice". This is a general principle, that will be defined different by everyone.
As with many aspects of the legal system, it is contextual - and the contextual nature is fundamental, not just "in addition".

As the context changes, so does the law.

So, is it possible to do evidence based legislation? No, not for the future. And it makes no sense to legislate for the past.