Some commentators have zeroed in on a potential tension between Justice Scalia's plurality opinion and Chief Justice Roberts' separate concurring opinion in Rapanos over the issue of judicial deference to an agency's statutory interpretation. This tension is interesting both because the Chief Justice joined Scalia's opinion, and because it may tell us something about how the Roberts Court will approach future agency interpretations of regulatory statutes, both in the wetlands context as well as in future cases.

Justice Scalia's opinion adopts a particular interpretation of the meaning of "waters" in the Clean Water Act. Further, as the Cato Institute's Mark Moller observes, Scalia's opinion stresses "that before an agency can reach local conduct under a comprehensive regulatory program, Congress must clearly authorize it to do so in the statutory text." Chief Justice Roberts, on the other hand, suggests that the statute is sufficiently ambiguous for the Army Corps of Engineers to "enjoy[] plenty of room to operate in developing some notion of an outer bound to the reach of their authority." Justice Scalia seems to know what the CWA means, and devotes much of his opinion to analyzing the relevant statutory text, whereas the Chief finds it fairly ambiguous. Are these two opinions really in conflict? I am not so sure.

Despite Justice Scalia's focus on the text of the statute, his opinion avoids claiming that the precise scope of CWA jurisdiction is clear, and that no deference is due to the Corps of Engineers. To the contrary, his opinion notes that that "'waters of the United States' is in some respects ambiguous," and acknowledges that there is some "ambiguity" as to where land ends and water begins. All that is clear, according to the plurality, is that "the Corps' expansive interpretation of 'the waters of the United States' is . . . not 'based on a permissible construction of the statute.'"

While portions of the opinion appear to be offering an authoritative interpretation of the term "waters" in the CWA, that is not what the opinion does. In administrative law terms, Scalia's opinion rejects the Corps of Engineers' interpretation at step two rather than step one of the familiar Chevron analysis. Indeed, Scalia quotes the step two test -- whether the agency has adopted a "permissible construction" of ambiguous statutory text - in rejecting the Corps' position.

I believe this reading of the plurality opinion eases the apparent tension between it and the Chief's concurrence. It also suggests that the federal government would retain substantial ability to go back and define "waters of the United States" in fairly expansive terms, even if it could not rely upon a fifth vote from Justice Kennedy for a broad interpretation of the Act.

Commenting on Chief Justice Roberts' concurring opinion, Moller offers the following interpretation:

If the agency deliberates about its constitutional and statutory authority in a "limiting way" in the context of public notice and comment procedures, he would give the agency "generous" deference, even [if]the EPA would draw lines different (and more expansive) than those that Scalia's plurality opinion draws.

I would agree. My point is that nothing in Justice Scalia's opinion necessarily contradicts this view. While I have little doubt that Justice Scalia would continue to read the CWA quite narrowly, his opinion offers the relevant agencies more wiggle room that it might at first appear.

NOTE: I offer some additional thoughts on the Rapanos opinion in this NRO column .