Criminal Procedure - As introduced, creates a law enforcement investigatory privilege; prohibits a subpoena from being issued for a civil or criminal proceeding for information protected by the law enforcement privilege. - Amends TCA Title 24, Chapter 1, Part 2 and Title 40, Chapter 17, Part 1.

SB 521 creates a new "law enforcement investigatory privilege" in Tennessee, protecting certain information gathered during active criminal investigations. It prohibits civil or criminal court subpoenas from demanding details covered by this privilege (such as evidence or witness statements) while an investigation is ongoing. The privilege applies until the case closes through dismissal, acquittal, or expiration of appeal deadlines. This directly affects law enforcement agencies (who gain protection for their investigative materials) and individuals or entities seeking such information through court subpoenas. The bill does not override constitutional rights or change standard subpoena procedures for law enforcement.