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While Republicans gasped as Chief Justice John Roberts joined the Supreme Court's liberal wing in upholding the federal health care overhaul, clues in the dissent suggest the conservative jurist may have originally sided against the law.

Perhaps the country will never know, but legal experts have seized on a string of passages in the dissent that indicate their opinion was originally written as the majority ruling -- one that would have struck down the law in its entirety.

Theories abound as to what clues the dissent offers. Did the minority justices simply set out to write their opinion with the confidence of a majority, without ever having five justices on board? Or did Roberts flip, perhaps under pressure to let stand an historic piece of legislation and/or battle the perception of the high court as partisan?

"I suspect ... the chief switched very late in the game," constitutional lawyer David Rivkin told FoxNews.com.

Read the dissent, which begins on page 127 of the opinion.

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Further, Rivkin speculated that the remaining conservative justices in the minority left a trail of clues for the public to find. "To say that they're angry, I think, is an understatement."

Skeptics like Rivkin point to:

  • The fact that the dissent repeatedly referred to liberal justice Ruth Bader Ginsburg's argument as the "dissent," suggesting she was at one time in the minority.   
  • The commanding tone of the conservative justices' language. 
  • The way the dissent addresses the pivotal issue of whether the law's so-called individual mandate penalty can count as a tax.

In its 5-4 ruling, the Roberts-led majority concluded that the penalty for not buying health insurance can be construed as a tax, and therefore fall within Congress' legal authority to tax.

But in the dissent, the anti-ObamaCare justices wrote about that argument as if it were never seriously considered -- referring to the argument as "feeble."

They described one detail against that argument as the "nail in the coffin," as if the claim had been shot down entirely.

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In a telling portion, the justices wrote: "Finally, we must observe that rewriting (the penalty) as a tax in order to sustain its constitutionality would force us to confront a difficult constitutional question: whether this is a direct tax that must be apportioned among the States according to their population. ... Perhaps it is not."

The justice then added: "(we have no need to address the point)."

Paul Campos, a law professor at the University of Colorado at Boulder, seized on this language to argue that the dissenters were originally in the majority. He wrote: "... the only reason the Court would not have to address this question is if the majority in fact refused to construe the mandate as a tax."

Campos suggested in a Salon.com opinion piece that Roberts switched his vote, and that the dissent makes this clear.

Hannah Smith, a former clerk for Justices Clarence Thomas and Samuel Alito, said another clue to suggest this was originally a majority opinion is that the justices referred to themselves as "we" -- language typically reserved for a majority ruling.

"It definitely has the flavor of something that looks like it was written as a draft majority to begin with, and then turned into a dissent," Smith told FoxNews.com. "Now the question is, of course, whose majority opinion was it? ... And we'll never know that."

Smith, who now works with a group that is suing the Obama administration over another part of the health care law, also pointed to the fact that the dissent referred to Ginsburg's argument repeatedly as the "dissent."

The meaning of those passages, though, is unclear.

Some have pointed out that Ginsburg was actually in the minority on the issue of whether the mandate was permissible under the Commerce Clause. Ginsburg thought it was, but most of the justices disagreed.

If that is all the dissenting justices were referring to, then referring to Ginsburg's argument as the "dissent" could be construed as correct.

But Rivkin and others said the rest of the dissent makes clear the conservative justices were referring to the liberal justices' entire argument.
Rivkin noted that in the key section on whether the penalty is a tax, the dissenting justices did not refer to Roberts' opinion. Instead they referred only to the argument of the "government."

"It debunks the government's tax argument. It does not debunk the chief's tax argument," Rivkin said. He said this suggests five justices were on board before one of them flipped.