Are you a Michigan public teacher who wants to leave your union? Sorry, you're too late.

Michigan is a Right-to-Work state, and teachers have the right to opt-out of their union—but only if they do so during the month of August, and only if they manage to find the top secret post office box that accepts union resignations, according to the Michigan Education Association.

It's a straightforward conflict: employees in Michigan won the legal right to leave their collective bargaining arrangements in 2012, but public employee unions—including the MEA, which represent teachers—want to keep as many dues-paying members in their clutches as possible. To that end, the MEA has mandated that teachers must declare their intention to opt-out during the month of August.

But that's not all. The MEA also requires members to send their union resignations to an obscure P.O. Box, rather than MEA headquarters. The Mackinac Center for Public Policy reports:

In an apparent effort to make it even more difficult or even stop school employees from exercising their right under right-to-work to not pay union dues or fees, the state's largest teachers union has quietly set up an obscure post office box address to which members must send the required opt-out paperwork. It's P.O. Box 51 East Lansing, MI 48826. Based on a letter the Michigan Education Association sent to members who had tried to get out, and discussions with some of them, resignation requests sent to the regular union headquarters address will not be honored. An extensive search of the union's websites found references to the post office box address on just one page of MEA's main website, and on one affiliate union's website. There is no record of this post office box address existing before this month. In the past, union members who wanted to opt out just had to send notification to the address of the MEA's headquarters in East Lansing.

When asked for comment by Mackinac reporter Tom Gantert, MEA declined to provide a rationale for its actions. It's hard not to see the new P.O. Box as a thinly-veiled attempt to make the opt-out process so cumbersome that members exceed the one-month time limit.

But there's some good news for teachers who missed the deadline: in June, an administrative law judge ruled that employees have the legal right to opt-out at any time, and the Michigan Employment Relations Commission is inclined to support that decision.