There's been a conservative majority in the state's high court since the 2008. Last year there was a SCOTUS case regarding gerrymandered districts that was thrown back to Wisconsin because the court said it was a "states issue."
This was the first time in 15 years the court could hand down a verdict like this, and it's about time. Wisconsin's legislative body has written itself a supermajority in the state houses even though the state is almost evenly divided between Republicans and Democrats.