Enjoy the brief victory... the state will appeal and win
It's a state sovereignty issue... they will appeal on the grounds that a federal judge has no authority to reverse a state court system's final say in the matter absent clear constitutional error.
Brendan was EXPLICITLY told before questioning began that "we can't promise you anything" in exchange for his speaking with them.
The judge, however, opined that this EXPLICIT statement that no promises were being made was "drowned out" by other statements that could have been interpreted as IMPLIED promises of leniency.
That's debatable... subjective... his opinion... i.e. not a "clear error" as is required in a state sovereignty matter.
If they allow the decision to stand uncontested, it will set an unwelcome precedent that would impact future cases... not to mention every convict in the Seventh Circuit's jurisdiction will be lining up to appeal their convictions claiming "Yeah, they said them things to me, too."
Wisconsin will also likely be joined by Illinois and Indiana in fighting the decision. As the other two states in the Seventh Circuit Court of Appeals, this decision impacts them as well.