Labor, Employment, Agency
Given hiring agency's lack of control over stage hands on the job and several other factors, NRLB certification of an exclusive representative was not supported by substantial evidence.
http://media.ca11.uscourts.gov/opinions/pub/files/201510429.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.