As a freshman senator, Barack Obama accused one of President George W. Bush’s judicial nominees of changing her approach from case to case to ensure outcomes favorable to powerful parties, like property owners. That one-sided record, he said, showed a mission of “not blind justice, but political activism.”

But in another floor speech soon afterward, Mr. Obama seemed to emphasize a different ideal than blind justice. Judges should “recognize who the weak are and who the strong are in our society,” he said, because hard cases will turn on factors like “the depth and breadth of one’s empathy.”

Today, as President Obama prepares to select a Supreme Court nominee to replace Justice David H. Souter, who is retiring, scholars and activists are confronting such contradictions as they scour his brief senatorial record for clues to his judicial philosophy.