A current debate in our society is whether judges make law, and, if they do, whether that is their proper role. There is an underlying assumption that making law is a new role for judges and reflects a liberal bias in the judiciary. Common law judges were said to interpret law implicit in the statutes or precedent cases. In this sense, they found law rather than made it. It was this process of interpretation that gave life to the common law. Most critically, in the colonial period England had no equivalent to the U.S. Supreme Court. Parliament and the king had final authority and could overrule the courts. In the U.S. constitutional system, the Supreme Court can overrule both the president and Congress. Judges in the United States today make law just as surely as do legislators.

The difference between finding and making law may seem inconsequential, but it has profound implications. The Constitution prohibits ex post facto laws—laws that punish past conduct that was allowed at the time. This means that if a state passes a law making it a criminal offense to prescribe amphetamines, that law cannot be applied to allow the prosecution of physicians who wrote prescriptions for amphetamines before the effective date of the law. However, if a judge finds a common law rule, such as an obligation to obtain informed consent from patients, then, in theory, this is just a new interpretation of the existing law. A physician who fails to obtain informed consent for a surgery performed before the first court decision on informed consent in the state could still be sued.

From the defendants’ perspective, there is little comfort in knowing that the judge did not make the law that they are accused of violating. Since the criminal law demands that the law be specific, most criminal law decisions are not retroactive. Some courts apply this same principle in civil law by making the new standards prospective when they dramatically increase a defendant’s legal duties. They warn potential defendants of the new standard of conduct without allowing them to be sued for past conduct. This poses a policy problem because it denies compensation to persons previously injured by the now proscribed conduct.