A New York Times editorial , citing a recent study , complains that Supreme Court nominees don't tell the truth during their confirmation hearings, which makes it hard to predict how they will behave on the bench. The study measures the degree to which a nominee expresses a commitment to respecting precedent during confirmation hearings and finds little relationship between that measure and the actual propensity of that person, once confirmed, to respect precedent. The Times is troubled: "Supreme Court nominees present themselves one way at confirmation hearings but act differently on the court. That makes it difficult for senators to cast informed votes or for the public to play a meaningful role in the process."
But, as the study notes, there is a correlation between ideology and willingness to overturn precedents: The five more-conservative members were those who were more likely to overturn precedents. There is a simple reason for this. The conservative Rehnquist Court inherited the liberal precedents of predecessor courts, especially the Warren Court. We know from other studies that justices tend to vote their political preferences. So if Republican justices are to vote their political preferences, and the precedents that they inherit are liberal, they are going to have to overturn those precedents.
The New York Times has little to complain about. It is easy to predict how nominees will vote once they are on the court. Just look at their party membership and other evidence of their ideology and ignore what they say at their confirmation hearings.