Hey short, these guys have answered your questions but i figured i would help out with a link if you want to go a little bit deeper into the subject:
http://americanmafia.com/Crime_And_Labor.html
This is from the guy who wrote To Kill the Irishman's site, it has a lot of into. Also i would suggest, i know it would take a lot of time but you would get the most info, go over old cases with labor racketeering that had with informants, find testimony transcripts and it will be a step by step tell all of how labor racketeering works. Also i would go over Lepke's fbi file and the case against him, most people create him with creating labor racketeering. Hope this helps,
Daniel Perrygin