Immunity from prosecution may be granted at the grand jury stage, CPL 190.45, as well as elsewhere in a criminal proceeding, typically at trial. Immunity is covered by article 50 of the Criminal Procedure Law and in article 190, regarding grand jury proceedings.
A louver (American English) or louvre (British English) is a window blind or shutter with horizontal slats that are angled to admit light and air, but to keep out rain and direct sunshine. The angle of the slats may be adjustable, usually in blinds and windows, or fixed.
Louvers originated in the Middle Ages as lantern-like constructions in wood that were fitted on top of roof holes in large kitchens to allow ventilation while keeping out rain and snow. They were originally rather crude constructions consisting merely of a barrel.