The Michigan Education Association has been illegally blocking its members from resigning from the union, the state's labor agency said Tuesday.

It ordered the union to start accepting resignations unconditionally, which could cause it massive membership losses. Labor organizations statewide could see similar losses if the ruling is applied broadly.

In three separate rulings Tuesday, Julia Stern, an administrative law judge with the Michigan Employment Relations Commission, said the teachers' union was unfairly restricting its members' rights under the state's new right-to-work law by accepting their resignations only during August. The judge also faulted the union for not publicizing the one-month opt-out period to its members.

The union had rejected any resignations it received the other 11 months of the year. It wouldn't hold resignation letters that were sent early until the next August period. Members whose letters were rejected or who simply thought the state's 2012 right-to-work law meant they no longer had to pay dues discovered that the union considered them to still be members and would report them to collection agencies for nonpayment of dues.

While the three orders are specific to the teachers' union, it puts the state on record as saying that such practices are labor law violations. That is significant because limited opt-out periods are a common response by unions to right-to-work laws. Other unions attempting to adopt such policies could face similar legal challenges.

Stern ordered the union to eliminate the August-only language from its bylaws as well as to post notices at all unionized workplaces announcing that it had committed unfair labor practices and alerting members to their rights.

"Aside from making the bylaws available through its website and publicizing the website, MEA does not regularly publish information about the window period in any of its publications or send information about the window period to its members," the judge noted.

The rulings involve three teachers' union locals covering the Michigan cities of Saginaw, Grand Blanc, Battle Creek and Standish-Sterling. The Michigan Education Association is the state branch of the three million-member National Education Association.

"As we have said all along, the bylaws of a membership organization do not trump state statute. The MEA, unfortunately, chose to treat its members not as professionals but as piggy banks," said Patrick Wright, vice president for legal affairs at the Mackinac Center for Public Policy. The center's legal foundation represented the plaintiffs in the Saginaw case.

"This ruling is a huge victory for workers throughout the state whose rights under Michigan's right-to-work ork law are being denied by unscrupulous union officials," said Mark Mix, president of the National Right to Work Foundation. The group's legal foundation represented the Battle Creek, Standish-Sterling and Grand Blanc plaintiffs.

A MEA spokesman could not be reached for comment.

It is not clear how many teachers have been prevented from leaving the union since the law was enacted. Teachers' union President Steve Cook said in October 2013 that his union had retained 99 percent of its reported 112,000 active members in the first year since the law passed.

However in March testimony before the Michigan Employment Relations Commission, MEA Executive Director Gretchen Dziadosz said 8,000 of its members were not currently paying dues. That suggests that many either assumed that they were longer union members or were simply refusing to pay.