General (ICAO)

ICAO Annex 13 §3.1 establishes:

"The sole objective of the investigation of an accident or incident shall be the prevention of future accidents and incidents. It is not the purpose of this activity to apportion blame or liability."

Consequences:

The safety investigation is strictly separated from criminal or civil proceedings.
Evidence, statements and reports of the safety investigation must in principle not be used for other purposes (apportioning blame, claims for damages, disciplinary action) — see Annex 13 §5.12 (Non-disclosure of records).
Safety recommendations generated address authorities, manufacturers, operators etc. with the aim of preventing recurrence.

Protected records (§5.12) include:

Statements taken from involved persons during the investigation,
Correspondence between persons involved in operating the aircraft,
Medical or private information about persons on board,
Cockpit Voice Recorder (CVR) recordings and transcripts,
Recordings from ATC units,
Opinions expressed in the analysis.

These data may appear in safety reports only if directly relevant to the analysis and not damaging other interests.

Europe (EASA / EU)

Regulation (EU) 996/2010 Art. 1 adopts the no-blame principle verbatim:

"The sole objective of a safety investigation shall be the prevention of future accidents and incidents without apportioning blame or liability."

Art. 14 protects sensitive safety information from disclosure in other proceedings (prosecution, disciplinary, damages). Disclosure is permissible only when a competent judicial authority finds the interest in disclosure outweighs that of confidentiality.

Art. 4 requires Member States to maintain an independent and permanent civil safety investigation authority.

Germany (national)

The Bundesstelle für Flugunfalluntersuchung (BFU) in Braunschweig is the independent authority required by EU 996/2010 Art. 4. Established by the Flugunfall-Untersuchungs-Gesetz (FlUUG).

§1 FlUUG adopts the no-blame principle. §17 FlUUG protects the confidentiality of investigation records in civil and criminal proceedings analogously to Art. 14 EU 996/2010.