Anyone interested in exploring Just Culture would do well to consult the work of Prof. James Reason or Dr. Sidney Dekker. What follows is loosely based on their research (please excuse me if I seem a little pointy-headed!).
Just Culture is a little more involved than some of us may believe. Nevertheless, it is actually fairly straightforward: it is about establishing a set of preconditions for any high-reliability organisation (including ATC) to function safely. Yes, it is about wider reporting of safety threats; no, it is not simply a set of prescriptive rules for incident reporting. You can't just take a chunk of it and weld it on to an organisation or its procedures. There are already rules which demand that all occurrences are reported in the interests of safety; yet these rules are sometimes ignored.
By its very nature, culture refers to a set of shared beliefs, values & norms - in this case around the issue of safety - held by a group. We may refer to such things as "management culture", or "team culture" for example. Therefore, the safety culture of an organisation is the set of values etc. which determines the safety-based behaviour of the members within that organisation. To be described as a "culture", these values must be reflected by all members.
A "reporting culture" is an essential part of just culture. Individuals should be able to communicate their safety concerns freely, and without fear of punitive action (unless warranted). From a human factors standpoint, Just Culture is about allowing that humans will continue to make errors, but not all of these should warrant punishment - the application of which hinders accurate reporting. Accurate safety reporting will be most effective only when all parties have a shared purpose for gathering such information. Yes, this may require a bit of a "leap of faith" in some units/companies. Nevertheless, as those involved in aviation safety, surely we have a duty to give the subject of Just Culture a thorough hearing.