In John Roberts' opening statement yesterday, he said:
Judges and justices are servants of the law, not the other way around. Judges are like umpires. Umpires don't make the rules; they apply them.
The role of an umpire and a judge is critical. They make sure everybody plays by the rules.
Baseball has a clear set of rules that umpires enforce. The Constitution, on the other hand, has a set of rules that don't necessarily apply to everything that happens in modern society. It is only the cases that don't fit nicely within the rules of the land that make it to the Supreme Court. A Supreme Court Justice must then interpret the Constitution to see how it applies to a particular case.
So, either Roberts doesn't understand the role of the Supreme Court (unlikely), or he is deliberately trying to distract from the real problem with his nomination.