It's unfortunate that we critique Supreme Court nominees today in ideological or political terms, because the Court is the nonpolitical branch of government. Justices are supposed to apply the law to cases before them--to call balls and strikes impartially, as then-Judge Roberts put it--not decide cases according to liberal, conservative or any other political values. Yet ever since liberals viciously attacked Robert Bork in 1987, that's the way we've judged nominees.
The reason is simple: In large measure, we no longer live under the Constitution. Instead, after turn-of-the-century Progressives came to power during the New Deal, the Court began reading the document not as a limit on government but as a font of endless government powers and programs.
But those programs would eventually have to be adjudicated in the courts, which meant judges would ultimately rule over vast areas of life that the Constitution had left either to the political branches or to private ordering under the common law. And since much of that adjudication would require judges to make not legal but value judgments, it would be important to know just what values they would bring to the court. Thus has politics trumped law, and a Constitution of limited government been turned on its head.
