Mr. Monk and the End - Part I - S8-E15
Continuity mistake: In 3-7 "Employee of the Month", Joe Christie says he was with Monk when he got the news of Trudy's death. He said Monk had been laughing, and that he never heard him laugh again. In this episode Monk and Stottlemeyer get called to the scene of a crime, a women's clinic. In this episode there is a flashback to the exact same location years earlier and to Stottlemeyer getting the phone call about Trudy's death. He and Monk were working a case that day and Joe Christie was not present.
Answer: The two men are trying to work out a secret deal between them without involving the union, which means the workers' interests aren't being represented and defeats the whole purpose of a union. The mayor would lose labor's support and Cusack's union troubles would just be starting.
Captain Defenestrator