Madison Teachers, Inc. Solidarity eNewsletter (PDF), via a kind Jeannie Kamholtz email:

MTI represents nearly 3,000 teachers in the Madison Metropolitan School District. Of that number, over 96% are members of their Union. That number has been rising since Governor Walker, as he described it, “dropped the bomb” on public employees and collective bargaining almost three years ago.
However, there are currently several hundred MMSD employees in the teacher bargaining unit who are not members of MTI. They choose to be “fair share” contributors – that is, they pay a maintenance fee to the Union for all of the rights and benefits MTI has negotiated for them and provides to them, even though they are not members of their Union. These individuals have no voice in what issues MTI pursues; how MTI is governed; and can’t vote on MTI contracts, or in the election of MTI officers.
Faculty Representatives in each school and work location receive, on a monthly basis, updated lists of members and fair share contributors. What can you do? Share this article with fair share teachers at your work location, and have a discussion about the many rights and benefits MTI has negotiated on their behalf over the last 45 years, e.g., a never-ending salary schedule, health, dental and life insurance, due process, retirement, TERP, leaves of absence, paid sick leave, paid holidays and FMLA integration, to name a few.