For years people have complained that work rules at the convention center were driving away convention business in Philadelphia.
A new management company said it needed more customer-friendly work rules. Four of the unions signed on by the May 5th deadline, but two did not - the Teamsters and the Carpenters.
So on Monday the Teamsters set up a picket line, but other union members crossed it.
By mid-morning all was quiet outside the Convention Center. Present were a few Teamster pickets, some private security guards, and City police.
However, things were far more contentious when John Dougherty, the leader of the Electricians Union, led his and three other unions past the picket line earlier in the morning.
Verbal insults were hurled at the entering workers, but in the end electricians, laborers, riggers, and stagehands entered and are now under a new labor agreement inside, doing the work of the Teamsters and the Carpenters.
The head of the Teamsters Local, Bill Hamilton, accuses Dougherty of engineering a deal to squeeze out the Carpenters Union from the Convention Center.
"I believe it's reprehensible that John Dougherty would show up in a picket line today and cross a union picket line. I think it's sets the union movement in Philadelphia back a 100 years," Hamilton said.
Dougherty says Hamilton is upset because he is aligned with the Carpenters and that alliance cost Teamsters a really good deal that the Electricians and three other unions accepted in return for work rule changes.
"He blew it. He decided to hitch his wagon to the carpenter and the two foot stepladder, and the handgun," Dougherty said.
The Convention Center said it needed work rule changes to make Philadelphia more attractive to convention organizers who had complained in the past about Philadelphia's work rules.
Two years ago, to win a major convention, the center's management says it appealed to the Carpenters for some help.
"We went to our union members, the Carpenters specifically, and said can we get a break on these work rules so we can bring the show in. We were told no and as a result we lost that show," Convention Center spokesperson Pete Peterson said.
"So now these new work rules, they will allow us to go out and demonstrate to our customers that we took their concerns seriously," Peterson said. "We're now competitive with other cities, in terms of enabling exhibitors to have the freedom to do what they can do in other cities."
The Carpenters Union has now filed a formal complaint over being shut out of the Convention Center with the National Labor Relations Board.
Forty members of the four unions who did sign on were busy working inside the convention center Monday. They're setting up for the World Congress of Industrial Biotechnology. It's a small convention that will host around 1,100 people between today and Thursday.