Rosen, of the New Republic, provides an analysis of John Roberts, based on whether he has a top-down (agenda-driven/ideology relative) or bottoms-up (precedent relative incrementalist) judicial philosophy. He uses Dean John Jeffrie's (UV's School of Law) tool for understanding this distinction.
Incremental Change in the Court: Bottoms Up
Scalia and Thomas are top-down judges who believe that the Constitution should be interpreted in light of its original understanding and are willing (Thomas more than Scalia) to overturn decades of precedents that clash with their vision.
Roberts, by contrast, has never openly embraced originalism as the touchstone of constitutional fidelity. He has been guided at every stage of his career by an effort to apply existing precedents rather than to transform them. So there are at least preliminary reasons to hope and expect that he may be a bottom-up, conservative incrementalist.
Roberts's writings, from his days as a college student through law school, and later as an appellate advocate and judge, suggest an aversion to grand theorizing that might lead him to take an incremental, rather than a radical, approach to constitutional change.
Roberts's dislike for broad, top-down theories is evident in his earliest writings. At Harvard College, he wrote his summa cum laude undergraduate thesis on the relationship between ideology and political change. In it, he demonstrated a Burkean interest in the way political movements evolve over time, rather than conforming to rigid ideologies imposed from above.
As a Supreme Court advocate, Roberts's most notable quality was his willingness to represent both sides of the political spectrum, unlike more ideologically driven advocates like Ted Olson, the former solicitor general. In addition to arguing on behalf of environmentalists, he was retained by primarily Democratic state attorneys general to represent their position in the Microsoft antitrust case. For Roberts, the willingness to argue any side of a legal question is a testament to his belief in the power of reason. Rather than seeing himself as a partisan, he prides himself on being a neutral lawyer, willing to use his professional talents to apply a given body of law, regardless of his own political views.
Roberts has suggested that, although he thinks the Court can legitimately strike down an occasional federal law as exceeding Congress's commerce powers, he has no interest in joining the Constitution in Exile movement in a sustained assault on the regulatory state.