I got curious about what legal authority the NTSB has. Here is what I found:
>like a cop, the NTSB can secure an accident scene and keep others away. It can examine the aircraft wreckage. It can have aircraft parts tested to help determine why the accident happened. It can even subpoena evidence. . . . If there is a lawsuit concerning the crash, the NTSB will not get involved. Not only is the NTSB’s report of the accident’s probable cause inadmissible, but the NTSB investigators are prohibited by law from testifying in court, even if they are served with a subpoena.
>The NTSB may issue a subpoena, enforceable in Federal District Court . . . For purposes of the Health Insurance Portability and Accountability Act of 1996 (HIPAA), Public Law 104-191, and the regulations promulgated by the Department of Health and Human Services, 45 CFR 164.501 et seq., the NTSB is a “public health authority” to which protected health information may be disclosed by a HIPAA “covered entity” without the prior written authorization of the subject of the records.
>like a cop, the NTSB can secure an accident scene and keep others away. It can examine the aircraft wreckage. It can have aircraft parts tested to help determine why the accident happened. It can even subpoena evidence. . . . If there is a lawsuit concerning the crash, the NTSB will not get involved. Not only is the NTSB’s report of the accident’s probable cause inadmissible, but the NTSB investigators are prohibited by law from testifying in court, even if they are served with a subpoena.
Source: https://www.aviationlawmonitor.com/2009/04/ntsb/the-ntsbs-li...
>The NTSB may issue a subpoena, enforceable in Federal District Court . . . For purposes of the Health Insurance Portability and Accountability Act of 1996 (HIPAA), Public Law 104-191, and the regulations promulgated by the Department of Health and Human Services, 45 CFR 164.501 et seq., the NTSB is a “public health authority” to which protected health information may be disclosed by a HIPAA “covered entity” without the prior written authorization of the subject of the records.
Source: https://www.law.cornell.edu/cfr/text/49/831.59