Scientific evidence alone is not sufficient basis for health policy.

of effectiveness. Although it may frustrate scientists when politicians are swayed by the possible electoral consequences of various policy options, few scientists (including us) would want to live in a society in which politicians completely ignored the views of those who have elected them as their representatives. Voting, free speech, debate, and the push and pull of politics must have an important role in what free societies choose to do if the concept of democracy is to be meaningful. We should remember that progress in public health from its origins in the late 1800s and early 1900s has been as much driven by politics as by scientific and technological innovation. For example, child labour and alcohol control laws were inspired by social justice concerns, with the scientific evidence for their effectiveness coming later. Without constructive politics, historical progress in public health would have been far more limited, as the example of AIDS illustrates more recently. More generally, societies have values that don’t need to be proved in randomised controlled trials and are appropriate over-riding considerations in policy. A rigorous study showing that people with an infectious disease could be cheaply and efficiently shipped off to colonies of isolation would be ignored in any humane society because respect for human dignity would rule out such a policy. Similarly, current research assessing whether the death penalty is cost effective or has a deterrent effect on crime may someday resolve those empirical questions, but it can never tell us whether the taking of a helpless individual’s life by the state is morally acceptable. That judgment falls on all our heads A rticles recently published in Addiction have reignited debate about David Nutt’s 2009 conflict with the then UK home secretary, Alan Johnson. After Professor Nutt publicly accused the government of ignoring science when formulating drug policy (for example, by overestimating the dangers of ecstasy), he was sacked as UK drug policy adviser. As with other contentious issues such as heroin prescribing, needle exchange, and sex education, many scientists think that the lesson of the Nutt controversy is that we must take the politics out of health policy decisions and simply “do what the science says.” Based on experience as researchers and as policy makers at the White House and United Nations, we argue that although science should inform health policy, it cannot be the only consideration.