There is a lot of talk in Canada over the past few years about the muzzling of scientists. The Conservative government has, quite rightly, taken a lot of flak for going out of their way to prevent scientists employed by the government from discussing their findings from the public. The reason why is crystal clear - they want to make decisions based on intuition, greed, ideology, or disregard for the environment and they don't want information out there that detracts from the stories they tell to justify their decisions. If the only story the public has access to is the official government line then those that object will lack concrete data to make their points.
I found an interesting article that supports government silencing of scientists on the grounds that public servants should, as part of their jobs, always support the decisions of those higher than them in the hierarchy. The author points out that their views have already been considered and presumably found wanting so therefore they should have nothing left to say on the matter and should support the decisions of their bosses. It is suggested that providing information that runs contrary to the decisions made would somehow 'undermine the trust essential to an effective working relationship'.
If government scientists were only being limited to not actively campaigning against policies they already had input on this article might have a leg to stand on, but that is not at all the case. As this rebuttal describes, many scientists have been prevented from giving policy neutral information about their research out to the public by policymakers. This is disastrous from the perspective of wanting an informed populace in general, but also greatly disturbing in that people trying to argue the benefit of policies such as other political parties are not privy to all the relevant facts. When the government has direct access to scientific information and prevents both the public and their opponents from accessing that information we cannot have a transparent and free society - the founding principles of effective democracy assume that the people can learn about what decisions are made and why.
Moreover we must remember that scientists are still citizens. They should be able to argue their positions and point out relevant facts just as anyone else can. Of course we should not assume that anyone in a white lab coat is an expert on public policy and assume that they are better qualified than the actual decision makers to make tough choices. Sometimes they will be right and sometimes they will be wrong but they need to be able to speak so that we can see which is which. When employed by the government people need to implement policies they may not agree with, that is certain, but they also need to be able to speak out about their feelings and the facts they are aware of so we can all see exactly what went into making a decision.
If the government's decisions cannot stand on their own merit when exposed to the light of day and the marketplace of ideas then they should not be implemented. Policymakers do not have to listen to any given scientist, nor bow to any particular agenda no matter how well supported by facts. What they should have to do is let all of us see exactly what the facts are so we can see the why and how of the decisions for ourselves.