First it was changes to pay, then evaluation systems, and then tenure laws. Now, lawmakers in several states are challenging collective bargaining, the foundation of teacher unionism. Leaders in Idaho, Indiana, and Tennessee are proposing bills that would limit what, if anything, teachers' unions could negotiate. None of the proposals has yet…

State-level battles over changes in education policy have shifted in many places from legislative chambers to courthouses, as unions and other critics of new laws challenge them on the grounds that they violate state constitutions and worker contracts. Republican governors and lawmakers--their ranks bolstered by the 2010 elections--won passage…