Thomas Miles and Cass Sunstein have now responded to critics of their study of judicial "activism" and ideological bias in Supreme Court review of administrative agency decisions. To briefly recap the Miles-Sunstein methodology, they code as "activist" justices' votes to overrule agency decisions instead of defer to them, and they characterize the justices as ideologically "partisan" if they are more likely to vote to strike down "conservative" agency decisions than "liberal" ones or vice versa.

In an earlier post, which Miles and Sunstein kindly cite in their reply, I criticized their approach on three grounds: that it fails to control for the underlying distribution of agency decisions (ignoring the possibility that an agency may make more flawed "conservative" decisions than liberal ones, or vice versa); that it ignored the fact that some justices may have centrist ideologies that skew their decisions just as much liberalism or conservative ones; and that their praise of Justice Breyer as the most "restrained" and "humble" justice may be misplaced in so far as he may actually have ideological reasons for maximizing the autonomy of agency bureaucrats.

Miles and Sunstein respond to the first of these points as follows:

If the distribution of agency decisions were skewed in a liberal direction, as some critics allege, we should have observed few or even no challenges from public interest groups. Instead, we observed a fair number of such challenges. Moreover, our study period included many decisions from both the Clinton and the Bush administration, and it would be a big surprise if decisions by the latter were mostly "liberal."

I don't think that if agency decisions were skewed in a liberal direction, it necessarily follows that there would be "few or no challenges from [liberal] public interest groups." The agency could skew in a liberal direction, but the public interest groups might want it to be skewed that way even more. Moreover, an agency skewed in a liberal direction may be more likely to be influenced by challenges from liberal groups to change its policies than one that is conservative. After all, a liberal agency is more likely to sympathize with the agenda of outside liberal critics. Thus, far from preventing challenges to its actions by liberal groups, a liberal-biased agency might actually attract them.

Moreover, the issue in question is not so much whether an agency makes "mostly liberal" decisions as whether it is more likely to err in its interpretation of the law in a liberal direction than a conservative one. If it does, than justices who are more likely to overrule liberal decisions than conservative ones may not be acting in a "partisan" manner, as Miles and Sunstein contend. For example, it's theoretically possible that an agency makes 80% "conservative" decisions, but that half of the 20% that are "liberal" are misinterpretations of the law, while none of the conservative ones are. In such a scenario, the agency makes many more conservative than liberal decisions, but the direction of its errors would still be skewed in a liberal direction. Contrariwise, we might get the opposite result if an agency is more likely to make conservative errors tahn liberal ones.

I am also not convinced that including the Bush administration necessarily protects against the possibility that erroneous agency decisions will skew in a liberal direction. The Bush Administration is a "big government conservative" group that has not paid much attention to regulatory reform, and that has strongly supported massive increases in domestic spending. It would not be surprising if in many agencies, a lot of decisions were left to the permanent bureaucracy (which is often liberal) and if many of those decisions would tend to skew liberal. Such a skew might even be acceptable to those Bush political appointees who approve of the massive growth of government that the Administration has presided over and (for the most part) supported. Probably, any such skew would be smaller than in a Democratic administration, but it may not be nonexistent.

I should emphasize that there are also theories that suggest that agency decisions are systematically skewed in a conservative direction rather than a liberal one. The Miles-Sunstein framework fails to address those theories either.

Lastly, I should note another problem with the Miles-Sunstein categorization scheme. As they note in their response to critics, "[a]gency decisions challenged by industry were deemed liberal, and those challenged by public interest groups were coded conservative." Since Adam Smith, free market advocates have recognized that business interests often favor government regulation when it suits their self-interested purposes. For example, businesses often favor regulations that hobble their competitors. Thus, the fact that an agency decision was challenged by "industry" doesn't necessarily mean that it was "liberal" (at least in the sense of being anti-free market). Similarly, a decision challenged by public interest groups isn't necessarily "conservative." There are now many libertarian and conservative public interest groups such as the Washington Legal Foundation that often challenge agency actions. As Miles and Sunstein correctly note, their coding methodology here is fairly standard in the field. But that doesn't mean that it is unproblematic.

UPDATE: Ed Whelan of the Ethics and Public Policy Center has also written a rejoinder to Miles and Sunstein's reply to his original critique of their study. See here.