A group that works to protect right-to-work laws in states such as South Carolina is looking to join a labor lawsuit Boeing Co. is facing over a new $750 million North Charleston assembly plant.

The National Right to Work Legal Defense Foundation said it is seeking to represent the interests of local Boeing employees by intervening in the closely watched case, said Mark A. Mix, president.

The National Labor Relations Board is suing the aerospace giant, saying its decision to build its new 787 aircraft line at Charleston International Airport was an illegal form of retaliation against the International Association of Machinists and Aerospace Workers in Washington state for past strikes.

Boeing has denied that and plans to contest the allegations. It said it picked South Carolina for the new assembly line based on numerous business factors, including a desire to offset the impact of future strikes at its highly unionized aircraft manufacturing hub near Seattle.

The NLRB is seeking a court order that would require Boeing to maintain the secondary 787 assembly line in the Pacific Northwest. If successful, that could stop the company from building the plane in North Charleston.

The federal labor board has faced a barrage of criticism from elected officials and others for bringing the lawsuit, including Mix's organization.

"They're really saying that private companies can't make a business decision," he said Monday.

His Springfield, Va.-based foundation's legal team is looking to persuade as many local Boeing workers as it can to provide affidavits and justify its request for an official place at the litigation table. The group has already heard from at least two unidentified employees who have expressed an interest in participating, he said.

"We'll take all comers," said Mix, who was in Charleston on Monday.

A judge who works for the NLRB will decide whether the foundation should be allowed to intervene in the law-suit.

South Carolina is one of 22 right-to-work states, meaning individuals cannot be forced to join a union as a condition of employment.

Mix said his foundation has taken 14 right-work-cases to the U.S. Supreme Court. He said he "absolutely" expects the Boeing case to go to nation's highest court if the NLRB's final ruling is appealed to the federal court system.

Mix said his worry is that the company will agree to a settlement that weakens right-to-work laws. A top concern is that Boeing will allow the machinists union to try to organize its local plant by signing cards -- a method know as check-card voting -- instead of by secret ballot, he said.

"It's got check card written all over it," Mix said.

Boeing spokesman Tim Neale said Monday the company is preparing for its June 14 hearing before an NLRB judge in Seattle. He had no comment on the legal foundation's efforts to recruit workers from the North Charleston plant, which is set to begin production in July. Boeing has already hired about 1,000 of a projected 3,800 workers it will need for the new 787 line.

Neale said he did not expect the lawsuit to affect the opening.

"Everything that we're planning to do we're still going to do down there," he said.

Contact John McDermott at 937-5572.