I must say, I don't understand the basis for the judge's ruling. I would think that is something the legislature can do for people not covered by a contract like teachers. And for teachers they could just include it in the next collective bargaining negotiation. I think the issue might be that the pension benefits are continuing. In other words, since they are probably based on some kind of long term service or vesting, changing the rules now makes you pay to continue benefits you have already earned. If they could do that then, taken to an extreme, why couldn't they simply require you pay 90% of your pay to the retirement system in order to continue to be eligible? That would of course be outrageous but some people would have no choice if they are near retirement or already vested in the plan but not yet eligible to retire. Perhaps that's what the logic is. Even though it is only 3%, it harms the employees economically.
I suspect that even if the ruling is upheld that the state will simply find a way to do it. But I don't think you should be too worried about it. They are not taking the money away from you per se, they are simply requiring that you contribute to your retirement. So the money is still yours. They are not contributing as much themselves but if you have a defined benefit plan then it really doesn't matter since you are entitled to a certain amount when you retire regardless of how much the state puts in this year. I know it sucks but it also makes your retirement system more secure so in the end it could be good for you.