Political decisions are made by those who have been elected to do so. As judges have not been elected by the people , they do not make political decisions.

To maintain the distinction between judicial and political decisions, the Founding Fathers anticipated that the judiciary would work free of political interference. Alexander Hamilton wrote:

"the complete independence of the courts of justice is peculiarly essential in a limited constitution."

To maintain full judicial independence, the Constitution clearly states, in Article III, that judicial power lies with the Supreme Court and the inferior federal courts established by Congress. The Article also clearly states that judges cannot be dismissed or receive unfavourable treatment simply because they make a judgement that does not find political support and/or favour from the party in power.
http://www.historylearningsite.co.uk/supreme_court.htm