Wolfgang Marx is a lecturer at the UCD School of Music, and he answers the question of whether and how experts should criticise government action they disagree on. Experts, even ones who officially advise the government, aren't required to form a united front the way a government does, but even so it can be self-defeating to get caught in political struggles. In response, Dr Marx suggests a way of dividing up the kinds of disagreements an expert can have with the government, and suggests when and how to disagree with the response, such as undermining faulty scientific justifications given for action when the field in question is the expert's own.
The main reason not to speak out is the need fro a united front when convincing people of the need to do something they don’t like. As discussed in another answer (Elmar Unsteinsson, “Is it ever right for the state to lie to us?”) under certain very specific circumstances, such as when avoiding panic, it is appropriate even for the government to lie to us. However, advisory panel members aren’t deciders themselves and are not formally responsible for anything (no “collective cabinet responsibility”, no “cabinet solidarity”), so this concept doesn’t apply here. But when should they express disagreement? What is important enough to risk breaking the united front?
If they disagree with something while there is no scientific consensus (distance 2 metres - 1.5 – 1), or where non-scientific considerations are relevant as well (proper masks for everyone may be advisable, yet may also deprive frontline healthcare workers of a sufficient supply – also, it may make people think they can now be less careful with regard to keeping the distance to others) they should probably hold back with public critique.
The risk is that they may become embroiled in political battles, even in party politics because it is often assumed that something is done out of personal interest. For example: there was a recent interview with UK government advisor (SAGE member) criticising the government’s claim that their decisions are always led by scientific advice: “they are not being led, they have never been led, they have been advised”. The interviewer asked "Why do you feel the need to point that out" and muses whether the scientific community was focusing on covering itself against the blame and defending itself "from an attack you feel coming?" By becoming part of the battle, rather than standing outside, the effectiveness of the scientific advice becomes reduced.
In today’s world: politicians do very strange things, interpreting their own rules in odd ways. What if the politician you advise suddenly (and without any advise from you, or even against it) shatters the united front? What if he or she suddenly recommends injecting detergents or drugs that have not been tested with regard to their effectiveness against Covid-19 (because, as he says, he has a good feeling about them)? What if the British government defends what virtually everyone not bound by collective cabinet responsibility and cabinet solidarity regards as a breach of the lockdown regulations, namely the government advisor Dominic Cummings driving his family across the country while being infected with the virus?
Responding to a politician’s recommendation to inject disinfectants or to treat an illness with an untested drug such as hydroxychloroquine falls directly into the purview of advisors. In such a case I think they are not just within their right to correct this statement, it is even their duty to do so. There is no scientific dissent on this issue, and lives could be lost if this recommendation is adhered to by some followers of the politician in question.
This also applies to the case of Dominic Cummings. While advisors here make ethical rather than scientific statements, they do so out of fear of the impact it will have on many people’s willingness to comply with the current restrictions, which in turn could have serious consequences with regard to a second wave of Covid-19. So again, I think they are within their rights and even have a duty to speak out in this case. But what can they do to minimise the risk of being dragged into party-political battles?
A good approach to this thorny is demonstrated by Anthony Fauci: don’t comment directly on the political decision at all, only speak about the scientific aspects related to them. He states that there is no scientific evidence that the virus was created artificially (conspiracy theories)) yet also that he can’t comment on whatever the secret services find out, or that there is either no evidence or as yet no sufficient evidence that certain existing drugs (such as hydroxychloroquine) will also help against Covid-19. This way he can speak relatively openly yet doesn’t actually comment on political or social aspects as such and leaves less of an open flank for ad hominem attacks.
In conclusion: for a government advisor, speaking out against a government decision is a serious matter, a decision that should be taken lightly. However, if politicians are the ones breaking up the united front and advocating something against which there is a scientific consensus advisors may find themselves having an ethical, a moral duty to speak out. In order to minimise the risk of being dragged into political battles or being subjected to the now very common ad hominem attacks a good way of doing that may be to avoid direct criticism of people or of non-scientific issues and decisions, instead focusing on the relevant scientific and medical issues, highlighting them over and over and again and let their listeners or readers draw the their conclusions themselves.