EVERETT — Delegates to the Machinists union’s international convention overwhelmingly passed a members’ bill of rights that, proponents say, increases transparency and empowers workers.

Machinists from Puget Sound led the campaign to amend the union’s constitution.

The new language explicitly states what many members of the International Association of Machinists and Aerospace Workers (IAM) assume: That they have the final say over accepting or rejecting a contract proposal, said Jon Holden, head of the union’s District Lodge 751, which represents about 35,000 workers in Washington. The vast majority of its members work for Boeing around Puget Sound.

Prior to the IAM’s Grand Lodge Convention earlier this month in Chicago, the union president had wide authority to negotiate with employers, schedule contract votes, and even approve a contract proposal that workers rejected.

Former IAM International President Tom Buffenbarger gave many District 751 members a lesson in his office’s power when in 2013 his office sidelined district union leaders in pushing through a concession-laden contract with Boeing. Local leaders opposed the contract. Members overwhelmingly rejected the first proposal, then narrowly passed a second proposal that included short-term compromises and kept the biggest long-term change: an end to Machinists’ pensions.

Buffenbarger’s power play left a deep rift between District 751 and the International, as the IAM’s headquarters is called. The district is one of the IAM’s strongest and largest lodges. The union has more than 500,000 members. It has seen a dramatic decline in dues-paying members in recent decades.

The conventions, which the union holds every four years, were strictly run productions designed to shore up support for Buffenbarger, who took over the top post in 1997, said several District 751 members who attended prior conclaves.

He resigned early this year and was succeeded by Bob Martinez Jr., a member of the union’s executive council.

By that time, District 751 activists were already several months into a grass-roots organizing campaign to curtail the international president’s power.

“We didn’t know if we would succeed, but these are changes that we needed to strive for” regardless the outcome, Holden said.

Soon after taking over as international president, Martinez met with District 751 leaders. He struck a conciliatory tone, and pledged to undo unpopular changes forced through by Buffenbarger, according to union members in the meetings.

Martinez also promised to back adding a members bill of rights to the IAM constitution. At the convention, he spoke in favor of the proposal.

“That’s huge when you have the international president telling the law committee that he supports” the amendment, said Lester Mullen, a longtime Boeing worker and president of District 751’s Local Lodge A.

Martinez could not be reached for comment.

The bill of rights says that only the union members covered by a contract proposal can approve or reject it, that local leaders will set when and where contract votes are held, and that only members covered by a contract can approve opening it up for negotiations early. It also prohibits union leaders from negotiating a contract with an employer without telling members.

“It’s up to members to decide” on contracts, Mullen said. “That’s vastly different from what it was in the past.”

The amendment addresses a laundry list of sins that critics accuse Buffenbarger of committing during the last Boeing contract negotiation. The International opened talks with Boeing without telling District 751 members, and two years early. The second vote was scheduled by the International right after New Years Day, a time when many senior Boeing workers are still on vacation.

The bill of rights shifts power back to members and makes it harder for an employer to play the International and local leadership against each other, said Holden, who was elected head of District 751 shortly after the second contract vote. The changes are “historic,” he said.

The district worked with Machinists across the country, building broad support for its proposal. “You can’t make changes that are good for you and not anybody else,” Holden said.

It is a step forward for the IAM, said Art Wheaton, a labor relations expert at Cornell University’s Worker Institute. “Having more transparency in unions is going to be good for labor in the long run.”

Passing the bill of rights will help heal some of the wounds lingering after the contract fight. However, more work remains to boost District 751 members’ confidence in the union and their labor rights, Holden said: “We need members to feel that they can make a difference” on the shop floor and in the union hall.

Engaging workers is critical to organized labor, which faces a tough challenge from the reinvigorated right-to-work movement, said Charlotte Garden, a labor law professor at Seattle University’s School of Law.

During his keynote address at the convention, Martinez promised to shift resources from IAM headquarters in Upper Marlboro, Maryland, back to supporting members and organizing efforts.

“Our lifeblood, our future depends on organizing,” he said.

The IAM will no longer allow representatives from “companies like Boeing that plead for our help one day in Seattle, then stab us in the back in South Carolina,” he said. “This is the same company who forced our members to make a choice between their jobs and their defined pension plan. They are no longer welcome at our meetings.

“I promise you that that tactic will never be forgotten or forgiven,” he said.

He also called out Lockheed Martin for actions it took following a 2012 Machinists strike there.

For past IAM conventions, Boeing and Lockheed Martin helped offset the cost of the event. No more, Martinez said. “We sent their money back.”

Dan Catchpole: 425-339-3454; dcatchpole@heraldnet.com.

Twitter: @dcatchpole.