Who selects the members of the independent/political commission?

In Michigan a current map can be challenged in the Supreme Court at anytime and can be struck down if deemed unfair. Each political party has the opportunity to challenge this process through an impartial federal court. How is this process "unfair"? Seems to me this would eliminate the need of an "independent commission". Who vets and chooses the members of the independent commission? How long do these members sit on the commission? Who chooses those who chose the members of the commission and how long do they sit in their respective positions? How are they vetted?