For what it is worth, I saw nothing to support Toobin’s claim that Thomas is disengaged and “not paying attention” during oral arguments. During the course of the argument (which was on a relatively prosaic statutory interpretation case), I saw Thomas confer with liberal Justice Stephen Breyer some three or four times, and with Justice Scalia once. I believe I also saw him look up some points in what seemed to be the joint appendix filed by the parties (or perhaps one of their briefs). Obviously, I could not overhear what Breyer and Thomas were saying. Perhaps they were discussing the weather or making plans for lunch. But the timing of their interactions make it likely that they were talking about issues raised in questions asked or about to be asked by Breyer, or one of the other justices.
I only attended this one oral argument (which was the first one I have seen in recent years). However, the fact that Thomas often confers with Breyer during arguments is well-known to court watchers, and has been noted by such knowledgeable observers as Washington Post Supreme Court correspondent Robert Barnes. Thomas himself has confirmed that he sometimes suggests questions to Breyer, who then poses them.
Obviously, there is plenty of room for reasonable disagreement about the quality of Thomas’ performance on the Court. Critics can legitimately claim that he should ask more questions at oral argument himself. But Thomas has a reasonable counterargument when he suggests that the justices would do better to listen to the arguments of counsel rather than take up much of time of with their own points. This is in fact how oral argument was conducted in the early nineteenth century, in the days of John Marshall and Joseph Story.
Be that as it may, Toobin is wrong when he claims that oral arguments are “the public’s only windows onto the Justices’ thought processes.” In reality, the justices’ written opinions are far more significant “windows…onto their thought processes” and explain their views in far greater detail and nuance than oral argument questions do. Obviously, many of the opinions are difficult for nonexperts to follow. But the same is true of many oral argument questions, whose significance can only be understood by observers with extensive knowledge about the case.
Thomas’ status as the Supreme Court’s most conservative justice and the nation’s most prominent black conservative inevitably makes him a controversial figure. Still, his reputation has gradually improved over the years, even among ideological opponents. Prominent liberal scholars such as Harvard’s Mark Tushnet (see also here) have come to recognize that he is a serious and sophisticated thinker on many constitutional law issues. Few any longer advance the old claim that Thomas just blindly follows Justice Scalia (the two have in fact differed on many important issues involving federalism, free speech, executive power, and other matters). On some key issues Thomas has influenced Scalia much more than the reverse.
Recognizing that leaves plenty of room for criticism, even sweeping criticism, of Thomas and his views. I myself think that Thomas takes far too expansive view of the scope of executive power in wartime, for example. I have plenty of other differences with Thomas, as well, such as on gay rights cases. I also believe that he should probably ask more questions at oral argument. But it is clear that Thomas takes the job seriously, and is very much engaged both at oral argument and – more importantly – outside it.