do not agree to any policy that could lead to a dismissal!
So you would say that no union should ever agree to a disciplinary process as these must have the ultimate sanction of dismissal. The unions and any company will therefore be in perpetual conflict and that is not healthy. What is healthy is for a company to agree with a union a mutually acceptable process for grievances. That is what happened between BA and Unite. It is no good whining when this process goes against you.
If there are individual cases where it is felt the process has gone wrong, fine, take legal recourse and go to tribunal. It is simply farcical to say that all cases are suspect and need looked at again. This is simply a smoke and mirrors ploy and I personally find it disgusting that supporters of rights in the workplace back moves whereby someone who had been sacked for bullying and harassment had another bite at the cherry.