Colas said the law violates the equal protection clause by creating separate classes of workers who are treated differently and unequally.
I am somewhat an expert on Constitutional Law, having studied it for more than 50 years. And I can state with complete certainty that the Wisconsin law does nothing to "create separate classes of workers who are treated differently and unequally." To begin with, all public union workers are treated equally under the law. The mere fact that they do not have the same rights as private unions has nothing to do with it because those unions, themselves, are not one in the same, or equal.
Case in point - both public and private unions are treated better than non-union workers. So, if Colas is right, then non-union workers are also being discriminated against. But the Constitution does not guarantee any right to belong, or to not belong, to any union. Nor does it allow for "extra" rights extended only to unions.
Therefore, by Colas' dumb opinion, every worker must belong to a union, and each union must be equal and the same, and each union must have the same rights and benefits. If one union negotiates higher wages, ALL unions would receive those same wages. And that would be so unAmerican as to be - SOCIALIST!
Colas also claims the law violates free speech and freedom of association. That is almost too absurd to even waste time countering. The law does not prevent either. Public union employees still may associate freely, and speak their mind. The only thing the law prevents is for employees whose pay comes from taxpayers, they cannot bargain collectively because they are bargaining for taxpayer, not private, money. Furthermore - and I'm sure this point escapes the small, limited mind of Judge Colas, employees being paid from taxpayer money do not have any inherent right to get more pay and benefits than those who are paying for them. Union workers get higher pay and better benefits than we, the taxpayers, get. A picture is worth a thousand words...
Here's a little understood point concerning public unions. All their pay and benefits come from the taxpayer, yet the taxpayers never get a chance to be included in the bargaining process. When was the last time you, as a taxpayer, was asked to vote on whether public employees got an increase in benefits? With private unions, the people paying (corporations etc.) get to sit at the table and negotiate and fight for their positions. Taxpayers cannot do that.
But what taxpayers CAN do is elect officials who will fight FOR them in the legislature by making laws that curb unions. And that is exactly what the taxpayers of Wisconsin did.