Opponents of televising court proceedings (in the Supreme Court and in other courts) often invoke fear of an observer effect. Knowing that what they say will be heard and that they will be seen by thousands or even millions of people will alter the behavior of lawyers and judges. They will play to the tv audience, the worry goes.
One can certainly point to high-profile court proceedings of the not-too-distant past as evidence for this observer effect, but perhaps one can also point to the current baseball playoffs. Last night's game between the Red Sox and the Rockies was played during what was at times a torrential downpour of the sort that, for a less high-profile game, might well have resulted in a rain delay. Yet the teams played on because (I strongly suspect) Fox Sports stood to lose its tv audience, for which it had paid a pretty penny, if the game were delayed. (Never mind that they lost much of the audience once the Red Sox lead grew to a laughable size.)
The Rockies experienced the same sort of tv-induced rain-soaked continuation of a game earlier in the playoffs and arguably the infamous "bug game" between the Indians and the Yankees was continued notwithstanding the swarm so as to hold the tv audience. Een if I'm wrong about the reasons for the non-delay of these games, television has already had at least one important impact on the baseball playoffs: the complete elimination of day games in favor of evening start times that will maximize tv viewership.
Now to the courts. One would expect that neither C-SPAN nor Court TV would have nearly the same impact on how court proceedings are conducted as commercial television has had on sports. It's hard to imagine a tv executive having much leverage in negotiations with CJ Roberts for oral arguments at night, for example. But even absent such changes, it's also hard to imagine that those who worry about the observer effect are entirely wrong. The knowledge that one is speaking to a million people rather than a few hundred makes a difference--even if the words spoken for the few hundred are eventually going to be more widely available. How big a difference live tv coverage will make seems the key question. The Supreme Court now makes oral argument transcripts available the same day that oral arguments are heard, while delaying the release of the audio recordings until the start of the following term. (See the policy here.) In very high-profile cases (e.g., Bush v. Gore), the Court has released audio the same day as the argument. In such cases, the Justices' questions and the lawyers' answers sounded much the same as in other cases, suggesting that the observer effect is negligible.
Still, even if there would be a substantial observer effect on the Supreme Court (or other courts) from cameras in the courtroom, at least part of that could be salutary. Although lawyers and Justices hamming it up for the cameras (if it occurred) would hardly be a positive development, greater transparency might lead lawyers and Justices/judges to speak in a way that is more accessible. My point is not that televising court proceedings necessarily improves them, only that it doesn't necessarily make them worse, on net.
In any event, given our free speech and free press norms, it's not clear that anything should turn on how one thinks this balance comes out. In the 21st century, the strong presumption of open courtrooms should mean really open courtrooms, i.e., televised or streamed live over the web.