Joseph Dougherty, one of the city's most powerful labor leaders and an unapologetic enemy of nonunion contractors, was found guilty Tuesday of using arson, intimidation, and violence for years to keep members of his Ironworkers Local 401 in jobs.

His conviction on charges of racketeering conspiracy and related counts of vandalism and extortion came after five days of apparently fraught jury deliberations. It was hailed as the final blow in a case that challenged long-standing business complaints over the tactics employed by Philadelphia unions.

Dougherty, a rough-hewn, tough-talking 73-year-old in pinstripes, sat stone-faced as the jury announced its verdict. He said nothing as he was taken into custody pending a sentencing hearing in April, at which he faces a mandatory minimum of 15 years in prison.

Supporters in the courtroom called out, "We love you, boss," as he was led away.

"He has worked long and hard to improve the lives of the men and women of Ironworkers Local 401," his lawyer, Fortunato Perri Jr., said afterward. "But we all knew this case presented a difficult task. We certainly respect the jury's verdict."

Asked what message he felt Dougherty's conviction on racketeering conspiracy sent regarding union relations in the city, Assistant U.S. Attorney Robert J. Livermore demurred: "Everybody has to follow the law. Nonunion contractors have to follow the law, too."

Those contractors, however, many still seething after past run-ins with violent ironworkers that slowed their progress and cost them thousands of dollars, were quicker to divine a more clearly defined message.

Sarina Rose, a vice president at Post Bros. Apartments, endured almost siege-like conditions as her company resisted ironworker threats while building the Goldtex Apartments at 12th and Wood Streets, just north of Chinatown. Union members stood outside the construction site berating employees, blocking trucks, and vandalizing property.

After work, tradesmen snapped photos of her children, ages 8 and 11, at their bus stop in Abington. They trailed her at weekend sporting events. One union leader loudly cursed at her in front of a packed restaurant and mimicked shooting her.

"I think [the verdict] says we have to find a better way of working together. Extortion is not the way," she said. "There is a more rational way to work together. This is not behavior to be tolerated."

The federal case against the ironworkers was arguably the most significant against a construction union since the 1980s, when federal prosecutors in Philadelphia brought a major racketeering case against members of Roofers Local 30-30B.

In the run-up to Dougherty's trial, 11 of the union's members pleaded guilty to charges ranging from conspiracy and arson to extortion. The list of their violent acts reads like a who's who of recent high-profile instances of labor strife.

They included the 2012 arson of a Quaker meetinghouse in Chestnut Hill, the baseball-bat beatings of nonunion workers outside of a King of Prussia Toys R Us store, and all-out brawls between the ironworkers and members of the Philadelphia carpenters union - all acts that Dougherty implicitly encouraged, whether or not he ordered them outright, Livermore said.

Throughout the union boss' trial, prosecutors played dozens of FBI wiretap recordings of Dougherty railing against nonunion builders in expletive-laden rants.

"He calls them pigs and he treats them worse than any pig should be treated," Livermore said during his closing arguments, adding that Dougherty "created a culture within the union where these acts were not only tolerated, but they were rewarded."

Prosecutors painted the union as one in which violence was deeply ingrained and Dougherty was a blue-collar Machiavelli steering the ship.

Members rose through the ranks by participating in goon squads that struck back at nonunion contractors who refused to hire their members. One group openly referred to themselves as "the Helpful Union Guys" - or "T.H.U.G.S." for short.

And ultimately, it was those union thugs who helped bring Dougherty down. Seven former ironworkers convicted in the case testified against Dougherty. They included one of his closest allies, business agent Edward Sweeney, who balked at the defense argument that the union leader was unaware of the acts of sabotage carried out by others.

"You're the captain of the ship," Sweeney testified this month, recalling a conversation with Dougherty. "You can't blame the navigator when you hit the iceberg."

Perri dismissed such testimony as last-ditch attempts by convicted criminals to avoid prison by blaming someone higher up the chain. He described his client's taped tirades as the "rantings of an aging man."

And the trial, which began Jan. 5, appeared to take a further toll.

Just after the jury began deliberating last week, Dougherty, who recently had a stroke and a heart attack, complained of breathing problems and was hospitalized. He returned to court the next day, and on Tuesday appeared to be in good health as he hugged and shook the hands of supporters outside the courtroom before the verdict was read.

Still, his lawyer urged the judge to allow Dougherty to remain on bail pending his sentencing so he could continue to receive treatment. Baylson denied the request, saying the law does not allow for such post-conviction release.

"I have to recognize the jury's verdict," the judge said. "Nobody likes to be placed in prison, but he's been convicted of the most serious crimes."

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