Because not being intimidated into unionizing is a bad thing.

WASHINGTON (AP) — The National Labor Relations Board says it will move ahead with lawsuits seeking to invalidate state constitutional amendments in Arizona and South Dakota that require workers to hold secret ballot elections before a company can be unionized.

The move comes after months of negotiations that failed to reach a settlement with attorneys general for the two states, according to an April 22 letter from the agency’s acting general counsel, Lafe Solomon.

It’s the latest in a series of high-profile steps the agency has taken to defend union rights since gaining a Democratic majority last year for the first time in nearly a decade. And it comes as Republican state legislators are enacting anti-union laws in many states as budget-cutting efforts.

Last week, the NRLB filed a controversial lawsuit that accuses Boeing Co. of putting one of its assembly lines for the new 787 in South Carolina — a right to work state — to retaliate against union workers in Washington state who went on strike in 2008.

Solomon told state officials he has directed staff to file the lawsuits against Arizona and South Dakota “shortly.” He claims the amendments conflict with current federal law that gives employers the option to recognize a union if a majority of workers simply sign cards, a process known as “card check.”

Solomon also claims the state amendments are pre-empted by the supremacy clause of the Constitution. That clause says federal law prevails if there is a conflict between state and federal law.

But Arizona Attorney General Tom Horne said the NLRB had no legal basis to file a lawsuit.

“There’s no statute that says people can’t have secret ballot elections, so there’s no preemption,” Horne said.