JAR-OPS has nothing whatsoever to do with PANS-OPS. If you're in JAR-land, you abide by JAR-OPS because they are rules (aka laws). Fail to abide by them and you end up with a fine or some time in prison, or both.
The PANS series of publications, like all other "document" type publications produced by ICAO are essentially a series of recoomendations on how to comply with relevant ICAO Annexes. And, of course, compliance with Annexes is mandatory for States (or they file a difference). If you've ever heard the expression "Acceptable means of compliance", that is what all the various ICAO "document" type publications are intended to provide.
In the case of PANS-OPS, where a State decides to implement it, it notifies this in its AIP, together with any necessary modifications to suit local operating conditions. Where a State has notified acceptance of PANS-OPS, its regulator is responsible for ensuring compliance. They do this by establishing appropriate legislation to ensure that everyone else complies with it too.
So PANS-OPS itself, is not a set of rules. However, it provides a framework for Contracting States to base their own rules on it.
After all that, I think that I prefer
keithl's answer!
