OPA 90: The recipe for success, lessons learned and further actions to be taken

There is an ongoing consensus in the shipping industry that Oil Pollution Act of 1990 (OPA 90) is by far the most effective implemented legislation worldwide. But what differentiates the success of this regulation from several other regimes concerning maritime like SOLAS, MARPOL, STCW, ISM or TMSA? Furthermore, should we expect any regulatory updates? And, is there further need to improve the level of understanding and the level of implementation of the OPA 90?