Lack of case law affords no protection. It just makes it hard to predict the outcome in advance.
So even in a situation where a court would award damages if a case was filed and malicious or negligent harm were proved, I'm not really sure it makes sense to say that anything was "prohibited" in advance.
New torts are invented, albeit rarely. Every so often there's a new duty of care in negligence. There are, I'm sure, other examples and the point is this: the lack of case law wasn't much help to the first defendant to lose on that point.