How is that different from a US law like HIPAA? The structures of the law seem largely the same, in that they give you guidelines to follow, but provide no clarity about what specifically is required by it and what isn't.
Understanding HIPAA has largely come from companies doing their best to comply with their understanding, and clarifications tend to come from courts when there's an actual dispute in progress.
Then, the US (through it's various district courts, circuit courts, the supreme court, and regulatory bodies) acts as the "judge, jury, and executioner".