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Will Chief Justice Roberts be in attendance after all?

Six Supreme Court Justices plan to attend tonight's State of the Union address, the same number as last year.

A court spokesman confirms the number, but the court isn't saying which of them will attend. Even so, it's possible to make a very good guess.

It's a cinch that the justices nominated by Democratic presidents will be there -- Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor, and Elena Kagan. As for the other two, Anthony Kennedy is very likely to attend, as he has at the last four addresses.

That leaves the sixth spot. We know it won't be Samuel Alito, who is in Hawaii for a long-standing speaking engagement. He wasn't on the bench Monday when the court handed down opinions, either.

My guess: Chief Justice John Roberts. He has attended every one of the speeches since he came on the court. And despite the dust-up over last year's State of the Union -- when President Obama criticized the court's ruling in the big campaign spending case and Roberts later called the annual event "a political pep rally" -- the mood this year is different. 

Members of Congress want to emphasize their ability to behave in a civil manner. Against that backdrop, a decision by Roberts to stay away would seem especially obvious. For that reason, it's highly likely he'll there tonight.

And now, the data: In the past 16 years, six is the largest number of justices to attend a State of the Union (or speech to a joint session of Congress in the years when it's not formally the State of the Union address). In 2006-2008, just four attended. Two came in 2002. Justice Stephen Breyer was the only justice to attend in 2001 and 2003-2005. And no justices at all came in 2000.