Don’t avoid the difficult issues, deal with them early on

In policy-making, there is usually a concern that is driving the agenda.  I’ve spent many years working on air quality. The concern was that ultra-fine particulate matter, PM 2.5, had the greatest health effects. Over time, with new studies and evidence, the idea became mainstream. The idea had been around for a decade or more. Legislators are never fast on the uptake.
What working on air pollution legislation taught me is that If you avoid dealing with the issue, it is not going to go away.  If the idea looks plausible it is likely the idea is going to become ingrained into policy thinking and take on the form of doctrine.
When that happens, whatever you say does not really matter. You’d have as much luck as an atheist of going to a Vatican Council, denouncing the Papacy and the Catholic Church. It may make you and your fellow travellers feel better,  but it is not going to persuade many Catholics.  Too often you’ll sound like David Icke talking about lizard people or Roger Helmer speaking against climate action.
So, the easiest way to deal with some claim against you is to respond to it early on, before the idea takes hold.  If you don’t,  it is likely it will take hold. Edith Efron makes the point that Rachel Carson’s ideas put forward in Silent Spring, 1962, was left unchallenged by the pesticide industry at the start. Over time, her ideas took hold in academia,  government officials, the upper class, and politicians. By 1975 the idea had become mainstream and the public accepted it. The laws taking the ideas forward had already been enacted.
You need to accept that most people are not going to believe what you say. Don’t take it personally. And, if you do take it personally, you better step back from any public-facing work to rehabilitate your issue.
The only way forward is to to take a leaf out of the book of Robert Caldini. Find someone who all seen as an independent expert and ask them to look at the issue. That means your usual roster of experts can’t be used.
This means you need to work back from when the law or policy is being drafted. Good evidence takes time to develop. It is usually not sitting in someone’s filing cabinet. You can take a leaf out of Kingdon’s playbook, and have the necessary studies sitting in your filing cabinet, ready for the day when policymakers or politicians ask for them.
If you don’t have the independent evidence and studies available when the issue hits the drafting table of the Commission or floor of the legislative chamber, you are too late.