yellow dog union

yellow dog union/ company union/ false-front union:
sindicato charro (Mx), sindicato proteccionista (Mx), sindicato corporativizado (Mx), sindicato patronalista (Col), la patronal (just Mx?), and the safest, for being widely understood in a mixed audience: sindicato falso

You don't hear yellow dog union too often in the US, but more in Canada, as I was reminded today. It comes from the term yellow dog contract.