The U.S. Supreme Court is taking another look at the constitutionality of mandatory union fees during its upcoming term, and experts say a ruling striking down such fees could significantly damage public unions' influence in Oregon.

But local union leaders say this case is just another attempt at undermining unions and that such a ruling would not spell the end of public unions in Oregon.

"Not only is it not the nail, we're nowhere near the coffin," said Brian Rudiger, executive director of SEIU 503, which represents some Oregon public employees.

A 40-year legal precedent allows unions in states nationwide to gather mandatory fees to pay for negotiations. This helps ensure there aren't any "free loaders" — employees who benefit from contracts negotiated by the union without having to pay for the effort.

In the current case, petitioner Mark Janus, a state child support specialist in Illinois, claims the AFSCME Council 31 fee requirement violates his First Amendment right to free speech.

Prognosticators expect the Supreme Court, with its new conservative justice Neil Gorsuch, to side against the union.

If so, it could be a "serious blow" to the financial well-being of Oregon's public unions, said Keith Cunningham-Parmeter, law professor at Willamette University.

"Unions are going to be seriously hampered in their ability to operate as they do today," he said.

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Part of the life blood of public unions is this mandatory fee and without it unions could lose significant political sway, which, he said, is part of the point — it is impossible to separate the legal and political aspects of this case.

Unions have long been a target for conservatives and pro-business interest groups because of their often adversarial positions.

Oregon unions regularly contribute large sums of money to political campaigns, endorse candidates and lobby for and against state policies. Mostly they throw support behind Democratic candidates who are considered more union-friendly.

"The writing is on the wall for public sector unions and it doesn't look good," Cunningham-Parmeter said.

Union representation has been falling in the United States for decades. In Oregon, 13.5 percent of employed workers were members of a union in 2016, according to Bureau of Labor Statistics data. This is higher than the rate for the United States as a whole, but down from the state's peak of 21.6 percent in 1989.

Among the culprits for the national decline are so-called "right to work" laws. Currently, 28 states have passed legislation that outlaws labor unions from compelling membership, which could expand to all states if the Janus case goes against labor unions.

Unions feared a negative result last year when a similar case out of California was heard, but the court deadlocked at 4-4 after the death of Justice Antonin Scalia a month earlier. The conservative Scalia was expected to align against unions as he had in previous cases.

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As with the last case on this issue, Portland lawyer Jill Gibson filed an amicus curiae brief on behalf of an Oregon client with a similar complaint as Janus.

She said she can understand the union's position against allowing non-paying members to benefit from union negotiations, but protecting First Amendment rights is more important.

"Those desires are so far outweighed by the constitutional rights of freedom of expression and freedom of association," Gibson said.

Gibson added that she hopes a ruling against unions would "return Oregon to a two party state," limiting what she sees as overwhelming financial support of Democratic candidates by unions, sometimes against the political views of their members.

University of Oregon political science professor Gordon Lafer said that such a ruling could create a snowball effect where the real consequences aren't realized for years as union membership, revenue and influence decline.

"Times are tight, and one of your bills was just declared optional," Lafer said.

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Oregon Education Association officials don't believe many people will leave the organization even if the ruling goes against it. John Larson, OEA president, said they have made a concerted effort over the past few years to connect with members to ensure the union is going in the right direction.

He said they aren't focused solely on this case, which the Supreme Court will hear this winter, but have prepared several budget and program scenarios depending on how membership changes.

"As long as we continue to focus on issues our members care about, we believe they will continue to be members," Larson said. "We will continue to weather the storm."

Contact the reporter at cradnovich@statesmanjournal.com or 503-399-6864, or follow him on Twitter at @CDRadnovich.