Final answer:
The authority to release health records for a mentally disabled adult typically lies with the legal guardian or someone with a legal power of attorney for healthcare matters. John's legal guardian would be authorized to release his health records.
Step-by-step explanation:
When it comes to authorizing the release of health records, the ability to do so for an individual who is mentally disabled depends on who has the legal authority to make healthcare decisions for that person. In general, if an adult is mentally capable of making their own decisions, they would be the ones to authorize release of their own health records. However, if an adult is mentally disabled and legally deemed incapable of making such decisions, the authority would typically be granted to a legal guardian or someone with a legal power of attorney for healthcare matters.
In this case, if John, the 45-year-old male, has been legally determined to be unable to manage his own healthcare decisions, and a legal guardian has been appointed, then the legal guardian would have the authority to release John's health records. Neither John's sister, nor the executor of his will, would have authority unless they have been appointed as the legal guardian or hold a power of attorney. It's important to note that rules and regulations regarding healthcare decisions can vary by jurisdiction, and it's always best to consult with a legal professional for specific cases.