Everyone knows that there are liberal US supreme court justices and there are conservative supreme court justices, and usually in a politically charged case you can pretty well predict the way the justices will vote by where they stand on the left-right spectrum.
But not always: the decision upholding Obamacare’s individual mandate was written by Bush-appointed Chief Justice John Roberts, and the decision legalizing same-sex marriage throughout the United States was written by Reagan appointee.