The chief justice’s invocation of precedent is the latest instance of his wont to take an ostensibly narrow and moderate approach that nonetheless yields a politically correct result sure to win praise in the nation’s leading editorial pages and law schools.

That this tendency arises when politically charged issues come before the court adds to the impression that Roberts is guided by political strategy as much as legal principles. When Roberts sided with the court’s conservatives this week in the Montana case and an important separation of powers case involving the Consumer Financial Protection Bureau, he could be confident the decisions would cause no protests in front of the Supreme Court. The same cannot be said of abortion, guns and immigration.

A conservative approach to the law will not always produce results that are politically conservative. But it eschews judging guided by ideological or political objectives. Roberts appears to be guilty of both.