After dueling rulings on a key portion of ObamaCare, influential Harvard law professor Laurence Tribe said he would not "bet the family farm" on the law surviving the next legal challenge.

In a 2-1 ruling, the D.C. federal appeals court invalidated ObamaCare subsidies for insurance obtained through the federally-run Healthcare.gov website. Later, a separate federal appeals court ruled unanimously that the subsidies are legal.

Tribe, who taught constitutional law to both President Obama and Supreme Court Chief Justice John Roberts during his distinguished career, explained on The Real Story this afternoon that it comes down to the language of the law. The question is over subsidies for enrollees in states that did not set up health care exchanges.

Tribe said he believes the case will come down to Roberts, predicting that the chief justice will rule with "common sense."

"He's not very likely in my view to take the language of the law, which says that exchanges established by a state are the ones on which people can get financial help, and emphasize that little word 'by,'" said Tribe.

Gretchen Carlson highlighted some criticism of Tribe by Michael Cannon of the CATO Institute, who said that Tribe is "obviously trying to coach the Supreme Court on how to rule for the government."

Tribe denied that he is trying to influence the court.

"I wish I had that influence. Even when John Roberts was a student of mine, he had a mind of his own," said Tribe, adding that Roberts is unlikely to side with an interpretation of the law that would "hold a gun to the head" of each state.

Watch the full discussion above.