"In the past six years, 38 judges have left the federal bench, including 17 in the last two years. If judicial appointment ceases to be the capstone of a distinguished career and instead becomes a stepping stone to a lucrative position in private practice, the Framers‘ goal of a truly independent judiciary will be placed in serious jeopardy. Inadequate compensation directly threatens the viability of life tenure . . . ."
The Chief Justice goes on to state:
Our judiciary will not properly serve its constitutional role if it is restricted to (1) persons so wealthy that they can afford to be indifferent to the level of judicial compensation, or (2) people for whom the judicial salary represents a pay increase. Do not get me wrong–there are very good judges in both of those categories. But a judiciary drawn more and more from only those categories would not be the sort of judiciary on which we have historically depended to protect the rule of law in this country.
These are two somewhat different sorts of arguments. The first argument strikes me as truly "constitutional" in the sense that a decline in the real value or perhaps even in the relative value of judicial salaries can be deemed a salary decrease in violation of the salary protection that Art. III affords federal judges. The Court would not hold that failure to increase salaries, even in the face of rapid inflation, violates Art. III, but Roberts appears to be saying that even if there is no judicial power to mandate a cost-of-living adjustment, Congress has a duty to ensure that inflation does not effectively reduce the salaries of Art. III judges. In Larry Sager's language, the obligation of Congress to ensure that federal judicial salaries keep pace with some benchmark (the Chief Justice uses legal academic salaries) is an "under-enforced" constitutional norm.
The second argument--that federal judges should not simply be the very wealthy or those who are used to lower pay--has something to be said for it, but it is not obviously of constitutional dimension. Such persons, by hypothesis, do not regard federal judicial salaries at current levels as a disincentive to serve, and thus their independence is not threatened by current salary levels. Indeed, one could imagine that Congress might, on policy grounds, want to keep federal judicial salaries where they are precisely because it wants to attract judges motivated by a sense of selfless idealism. The Chief Justice says in his report that federal judges, even with a salary increase, would continue to be motivated by a sense of service, and I tend to agree with that, but Congress could draw a contrary conclusion on policy grounds. Perhaps we can understand Roberts to be making a constitutional argument if we interpret him to be saying that the President and the Senate can make idealism a criterion for judicial selection, but they can't use a de facto pay decrease as the mechanism for ensuring such idealism.