Strictly speaking, there is no requirement that the government take its lessons from experts, either in the UK, the US, or elsewhere. They only ever do so in order to justify policies that they were planning on doing anyway.
In the US Constitution, there is no provision that mandates the use of experts on anything, and this has had some odd effects, in that laws and policies are based on their popularity and not necessarily on their efficacy. For example, the Supreme Court has had rulings that quite clearly state that the definition of insanity is not, and never will be, based on scientific understanding of mental illness, even if the scientific understanding advances beyond the legal understanding.