16 U.S. Code § 5708 - Administrative matters
Panel members and alternate Panel members who are not State or Federal employees shall receive compensation at the daily rate of GS–15 of the General Schedule when engaged in the actual performance of duties.
Travel and other necessary expenses shall be paid for all Panel members, alternate Panel members, United States members of the Joint Technical Committee, and members of the Advisory Committee when engaged in the actual performance of duties.
Except for officials of the United States Government, individuals described in subsection (b) of this section shall not be considered to be Federal employees while engaged in the actual performance of duties, except for the purposes of injury compensation or tort claims liability as provided in chapter 81 of title 5 and chapter 71  of title 28.
 So in original. Probably should be chapter “171”.