Why Secrecy At The US Supreme Court?

In a CNN article The secret Supreme Court: Late nights, courtesy votes and the unwritten 6-vote rule  Joan Biskupic,  tells us that the justices have a weekly meeting in secret.

"At their weekly private sessions, the nine decide which pending petitions to take up and, separately, cast votes on cases that already have been argued."

Justice Stephen Breyer is quoted:

"Regarding the general need for confidentiality, Breyer said, 'Transparency is usually a word that means something good, but I would say about the conference, it's important not to have transparency. ... It is very important for people to say what they really think about these cases, and that's what happens. So I worry about changing that and somehow bringing the public into the conference.'" (emphasis added)

 This really needed to be followed up.  Here are some questions I would have wanted to ask in that interview. (I recognize that these things might not come immediately to mind in the interview, but Biscupic is  described by CNN as 

"Joan Biskupic, a full-time CNN legal analyst, has covered the Supreme Court for twenty-five years and is the author of several books on the judiciary."

These are Supreme Court justices with lifetime appointments.  They can't be fired for what they say unless it rises to the level of impeachable by the US Senate. 

Justice Breyer, can you give some hypothetical examples of the kinds of things justices say that you think they wouldn't say if these meetings were public?

It's not that their language or behavior is objectionable because you say:

"What happens," Breyer told CNN, "is it's highly professional. People go around the table. They discuss the question in the case ... the chief justice and Justice (Clarence) Thomas and me and so forth around. ... People say what they think. And they say it politely, and they say it professionally."

Are there people outside the court who they feel accountable to and they would feel compelled to hide their real thoughts so these people wouldn't hear them?

If, for example, someone appointed to the court based on the strong support of the Federalist Society.  Do they say things that organization might object too?  If they said those things at these meetings, isn't it likely that other justices also appointed through the efforts of the Federalist Society would let that be known to the Federalist Society?

Is it because they are polite and reasonable to justices that their 'side' dislikes and that would be embarrassing?  

Are there things you might self-censor if this were to be public?  Why?

Is there an issue that what they say might reveal a bias for or against potential litigants at the court? 

Do they tell jokes that might be offensive to some groups in the US population? 

Are there concerns that US Senators who voted for a judge would regret that vote?  So what?  I mean simply, what would be the consequence to the judge?

Are you Ms. Biscupic perhaps too close to the court that you are reluctant to push Breyer beyond some line of appropriateness?  Would a different reporter who didn't have a relationship with the judges feel more comfortable asking such questions?  Or would such a journalist simply not have the access you have?  And would pushing further to ask these sorts of questions jeopardize your access to the justices?  I know nothing about Ms. Biscupic.  I could be totally wrong here.  I do know there have been concerns that the White House press falls into a relationship with the President and his press secretaries that can be jeopardized by asking unacceptable questions.  That's probably true about journalists who cover the court as well.  

Again, these justices have lifetime appointments.  What do they have to hide at this point?  And from whom?  I'd surely like to hear Justice Breyer or other justices answer these questions.  

I'd also note that I have, in the past, studied the concept of privacy in government, quite closely.  Nearly all public officials fear public scrutiny and in this day and age of social media, any ill-advised words could easily be copied out of context and tweeted to the world.  But Congress has adapted to C-Span.  And justices who feel the same concerns about becoming viral sensations would have a better understanding of the concerns that everyone else has.  

I would argue that all groups that are used to being able to talk, unaccountably, in private, resist when that protection is challenged.  

I recall working hard to get the Anchorage Municipal Assembly covered live by the local cable company when they arrived in Anchorage in the mid 1980s.  Assembly members on all political sides voiced concerns that such exposure would change how members debated.  But after a couple of months it quickly became obvious that a) citizens were tuning in and b) that assembly members forgot the cameras were running and didn't really change their behavior.  Recent turmoil at the Assembly was available for all to see first hand and not simply depend on how the media reported it.

So I would hope that journalists who have access to Supreme Court justices do dig deeper and push the judges to voice exactly how and why they would not be candid if the meetings were public.