Despite the landmark Supreme Court ruling this summer barring public-sector unions from requiring nonmembers to pay so-called agency fees, workers in several states say unions are either flat-out ignoring the decision or establishing a frustrating maze of procedural roadblocks to avoid compliance.

The June decision in Janus v. AFSCME sent shockwaves through organized labor in the U.S., holding not only that public unions violated the First Amendment by taking money out of unwilling workers' paychecks to fund collective bargaining, but also that employees must "clearly and affirmatively consent" before any fees or dues are collected.

Janus could end up costing unions hundreds of millions of dollars in California alone, where workers who filed an earlier suit say the case should apply retroactively, alleging that the Service Employees International Union (SEIU) retained members not through their "clear" consent, but through convoluted and difficult "opt-out" procedures. The nation's largest union, the 3-million-member National Education Association, announced plans to cut nearly $40M from its budget after Janus, amid fears it would lose hundreds of thousands of members.

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Faced with those challenges, workers' rights advocates say some unions and state governments have decided to effectively defy the Supreme Court.

"We're seeing huge problems across the country," Diana Rickert, the vice president of the Liberty Justice Center, which represented the plaintiff in the Janus case before the Supreme Court, told Fox News. "There is almost no government in America that is fully complying with the Janus ruling."

She said this includes unions not seeking "clear" consent with members as prescribed by Janus, or even using intimidation tactics to keep members on the rolls.

While the Liberty Justice Center has sent cease-and-desist letters to 11 states, from Ohio to New York, demanding that state officials comply with Janus, Rickert said litigation will be necessary in some instances to force states to follow the law.

"What we're up against is a national manipulation campaign led by government unions who want to stand in the way of workers exercising their rights," Rickert said. "Government union officials across the country are trying to scare and intimidate people into maintaining membership by making threats – they say things like, ‘Your salary will go down if you leave the union’ or ‘You’ll lose your benefits.'"

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In other instances in states including California and Minnesota, Rickert said, workers have been told they can only leave unions at some specific window in the future.

That was allegedly the case in Washington state, where several workers sued the government last month after being told they would have to wait until an "escape period" next year to leave their union. The Washington-based conservative Freedom Foundation brought the case against the Washington Federation of State Employees, saying it had "pressured" and misled employees.

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The Freedom Foundation announced late last month that Janus had left the SEIU "no choice" but to settle a lawsuit by public-sector nurses who asserted that their union had been skimming fees from their paychecks without their consent. The union returned the fees and, additionally, agreed to stop collecting fees absent clear consent.

That second part has proven something of a sticking point for public-sector unions. Rickert said many state government employers are still violating Janus by not obtaining clear and affirmative consent from existing members who had consented to join unions prior to Janus -- when they faced a much narrower choice between paying mandatory agency fees, or opting into the union and, in many cases, paying a similar or identical amount of money.

That is also an issue in the pending Washington case, in which the the Freedom Foundation argued, “it’s impossible for a worker to have knowingly waived a right that wasn’t recognized by the court until the Janus ruling was issued.”

For their part, unions have denied any strategic effort to defy the new Supreme Court decision.

"SEIU’s local unions are in compliance with the Supreme Court directives in Janus," SEIU spokeswoman Sara Lonardo told Fox News. She added that the California suit against the SEIU local union there "lacks merit."

But in a statement shortly after the Janus decision, Greg Kelley, president of SEIU Healthcare Illinois Indiana Missouri & Kansas, presaged the ongoing fight against the ruling.

“What the court and these groups don’t realize ... is that workers will not be deterred by such rulings and will continue to organize and unite to win fair wages and benefits while also providing the care and services that taxpayers want and deserve," Kelley said.

There are signs the fight may not be over soon.

Some legal experts, including UCLA Law Professor and First Amendment scholar Eugene Volokh, have suggested that states might be able to perform a constitutional end-run around Janus by directly funding unions using general tax revenues, rather than taking funds directly from individual workers' paychecks. Officials in some states, including Hawaii, have floated measures along those lines, which Rickert said would lead to additional legal challenges grounded in the same fundamental principle.

"This case is about giving workers a choice and a voice," Rickert said. "Not tricking, intimidating or coercing people into union membership."

Fox News' Kaitlyn Schallhorn contributed to this report.