This very smart lawyer isn't very smart when it comes to the Supreme Court and its role in American politics. She is referring to what is jokingly called the "ham and eggs" school of jurisprudence. It holds that judges are not constrained in their opinions. Their decisions are based on whatever they eat for breakfast, hence "ham and eggs." Justice Brennan, the great upholder of civil rights and liberties, told his law clerks privately that the test for constitutionality was what five members of the court decided was constitutional.
This is not how it works in practice. Supreme Court justices don't grow under cabbages. They are bred in many ways. Socializations occurs on many levels - their family, religion, elite schools, law review, etc. They must write opinions that explain their reasoning. In order to do this, they must build consensus within the Court. I've heard many justices, from both parties, describe how in the course of reading their colleagues' opinions, they change their own. In controversial cases, a majority and minority opinion will be written. Justices may also concur or dissent on their own.
Politics is an integral part of the judicial process. These justices are not hum drum, have no political opinion types, who are tapped to serve on the Court. They almost always have extensive prior experience in politics. They don't always side with the party of the President that nominated them but they usually do b/c their philosophy is consistent with that party's world view.
Countless volumes, op-ed pieces, law review articles and other forums have debate the way they work. I wish I knew more how judges work in other common law countries, such as England,and code countries such as France or Italy. It might throw a lot of light on what is essentially American in the process.
Law is not throwing i ching or using a ouija board. I frequently disagree with their decisions. The word for it is democracy. The US Constitution sets up a democratic republic.