49 CFR 109.5 - Opening of packages.
(a) In general. Except as provided in paragraph (b):
(1) Stop movement of the package in transportation and gather information from any person to learn the nature and contents of the package;
(2) Open any overpack, outer packaging, or other component of the package that is not immediately adjacent to the hazardous materials contained in the package and examine the inner packaging(s) or packaging components.
(b) Perishable hazardous material. To ensure the expeditious transportation of a package containing a perishable hazardous material, an agent will utilize appropriate alternatives before exercising an authority under paragraph (a) of this section.