As traditional world religions have withered in the modern age (in favor of a new scientific pseudo-religion), science has been increasingly pushed as its replacement in legal inspiration. It isn’t uncommon for Americans to argue in favor of pure empiricism as the basis for decision making in sphere of governance. Though well intentioned, this attitude has placed science into a role it simply wasn’t intended to fill. Science cannot inform most political decisions sufficiently: decisions over budgets, abortion, immigration, and even environmental regulation are not appropriately addressed.
The most immediate problem with science as a basis for law is the inherently changing nature of scientific knowledge. It is, by design, ever changing. The scientific process requires previous knowledge to be updated, theorems to change, and paradigms to shift. The history of eugenics in the United States is no secret; in fact, it was an inspiration for German National Socialists in the 1930s-1940s. Eugenic policies existed in the States for many years before and after the fall of Nazi Germany. If we entrust all of our legal decisions to science, we risk a repeat.
Though valuable as a path to knowledge, science is merely a process. It is entirely amoral. Science may tell us truths, but there are many philosophical and moral areas in which it is entirely uninformative. For example, in the realm of medicine, science is extremely useful to learn the risks, benefits, and many of the consequences of a given procedure or treatment. However, it cannot tell us whether or not a procedure should be used. An organ transplant may certainly save a life, but science cannot answer whether or not it is moral to take an organ without consent, even if from a dead body. In the realm of morality, it is better (albeit less productive) to look to philosophers.
Science observes people as merely parts of a system. From an empiric point of view, given enough knowledge of a system, it would be hypothetically possible to predict a person’s exact behavior. This obviously calls the idea of free-will into question. Whether accurate or not, this undermines the value of human lives in a political system. Consciousness as a chemical reaction holds no objective value. This kind of empiricism is obviously arrogant in its assumptions of the world. Still, governance requires a degree of idealism; a tendency to see the world not merely as it is, but how it may be. Science cannot provide the imagination needed for governance, only facts to shape it.
Of course, science shouldn’t be discounted entirely from the legal realm. Certainly, there are many decisions in which science has been overwhelmingly valuable, for example the outlaw of DDT in agriculture. Other decisions are more ambiguous. To wield science effectively we must remember its limitations. Simply trusting consensus at a moment may lead us to the wrong decision. In energy, the push toward solar power was driven by confidence in lower carbon emissions. This consensus was strong but overlooked the impact of extracting the minerals needed for panel manufacture. Now the tradeoff of these energy systems is a subject of controversy. Science can illuminate truth, but it does make errors.