Scientists as far away as the Royal Society in London cheered on 20 January when US President Barack Obama promised in his inaugural address to “restore science to its rightful place”. In the US federal science agencies, where staffers were holding inaugural parties of their own, many were elated at his words.

The eight-year Republican administration of outgoing President George W. Bush is regarded by many, if not most, researchers as a dark time for scientific openness in the United States. It was a time in which politically appointed officials censored technical reports that conflicted with the administration's conservative agenda, and ignored scientific advice on issues ranging from contraception to stem cells to climate change. With just six words, Obama had declared that era at an end.

But researchers need to remember that the task of restoring science is not down to the new president alone — they too have some work to do. The acrimonious tone of the Bush years has drawn scientists of all stripes into the political sphere, if only to defend their research from partisan attack. During the election campaign, moreover, many US scientists actively supported Obama against his Republican rival John McCain. But those same scientists must now take a step back to ensure that their newfound political activism does not compromise their scientific integrity.

Scientists who now view Obama in almost messianic terms should try to be more realistic and sceptical about his administration.

This does not mean that scientists should diminish their involvement in political life. Quite the opposite: policy debates on issues such as climate change and energy independence depend so heavily on scientific input that scientists can hardly escape being involved. Nor should they: if responsible researchers do not offer their opinions on policy, others will — as happened during the 1990s when a group of scientifically marginal sceptics tried to dominate the policy debate on climate change.

The many scientists who now view Obama in almost messianic terms should try to be more realistic and sceptical about his administration; the new team will make mistakes, too, and should hear about them when it does. And researchers should remember that political winds can change. The Republicans will at some point be in the majority again, and lines of communication need to be kept open.

Perhaps most importantly, scientists must not fall into the trap of believing that their research necessarily supports a single course of action — partisan or otherwise. Scientists can tell policy-makers what the consequences might be if, say, atmospheric concentrations of carbon dioxide were to stabilize at 400 or 600 or 1,000 parts per million. But they cannot tell policy-makers what level the world should work towards, because that depends on what consequences people are prepared to accept — especially when weighed against economic or energy needs. Such a decision is a political matter. So when scientists are acting as advisers, they must be willing and able to set their personal preferences aside and examine a range of possible outcomes. And when they are speaking on their own behalf — as is their right as citizens — they must convey such an endorsement as opinion, not as a scientific finding.

As a corollary, researchers must also continue to speak out against politicians who pick and choose data to support their preconceived conclusions, as the Bush administration was accused of doing when it systematically played down evidence for climate change, or for the ineffectiveness of abstinence-based sex education. Wise policy, like good science, is possible only when decision-makers look at all the facts — and understand all the uncertainties in those facts.

For thousands of researchers in the United States and abroad, Obama's words promise a new era of openness and an elevation of science in political life. Science may be restored to its rightful place, but it will be up to scientists to ensure that it stays there.