Roberts had begun to focus on a different argument to uphold the law and the mandate's penalty by defining it as a tax. That strained argument had received almost no attention in the lower courts, which had uniformly rejected it. It was seen as a long-shot by the law's supporters.
It would have been far easier, legally, for Roberts to have followed the rationale of two conservatives who voted to uphold the law in the lower courts: Appeals Court Judges Laurence Silberman and Jeffrey Sutton.
In separate opinions for the D.C.- and Cincinnati-based federal courts, Silberman and Sutton wrote that the mandate had not exceeded Congress' commerce power.
Roberts surely could have gotten the liberals to join a decision that the mandate was similar to a 1942 Commerce Clause case involving a farmer who was producing wheat for his own use and had no intention of selling it. In that seminal case, the Court ruled the farmer's wheat production nonetheless affected Commerce, and Congress therefore could regulate it.
In the health care case, since no one was urging the court to overturn that precedent (Wickard v Filburn), the court could have issued a narrow opinion. It could have ruled that since it wasn't being asked to depart from settled law, the health care act would stand, based on prior precedents.
Instead, Roberts focused the majority opinion on a much more difficult legal proposition: The tax power.
But Roberts also would limit Congress' authority in future cases under the commerce power.
Roberts then engaged in his own lobbying effort - trying to persuade at least Justice Kennedy to join his decision so the Court would appear more united in the case. There was a fair amount of give-and-take with Kennedy and other justices, the sources said. One justice, a source said, described it as "arm-twisting."
Even in Roberts' opinion, which was circulated among the justices in early June, there are phrases that appear tailored to get Kennedy's vote. Roberts even used some of the same language that Kennedy used during oral arguments.
During the arguments in March, Kennedy told Solicitor General Donald Verrilli:
"Here the government is saying that the federal government has a duty to tell the individual citizen that it must act, and that is different from what we have in previous cases - and that changes the relationship of the federal government to the individual in a very fundamental way."
Roberts wrote in the section of his opinion analyzing the Commerce Clause:
"Accepting the government's theory would give Congress the same license to regulate what we do not do, fundamentally changing the relation between the citizen and the federal government."
On the surface, Kennedy would appear to have been Roberts' best shot to persuade. The other three justices - Thomas, Antonin Scalia and Samuel Alito - are seen as more solidly conservative and much less susceptible to pressure.
After all, it was Kennedy who "betrayed" conservatives in 1992, when he flipped his vote in a key abortion case that could have overturned Roe v. Wade, the landmark decision that guaranteed a woman's right to abortion.
In the 1992 case, Planned Parenthood v. Casey, Kennedy initially was with conservatives, but then forged a last-minute alliance with Justices Sandra Day O'Connor and David Souter to put Roe v. Wade on more solid ground than even the original decision itself.
Kennedy has long frustrated conservatives, because he occasionally joins with liberals to provide the key swing vote in cases involving social issues. They openly mock his writing style as grandiose and his jurisprudence as squishy - in other words, changeable and too moderate.
That's not entirely fair to Kennedy. In fact, there are underlying and consistent themes in his jurisprudence, much more so than in the jurisprudence of O'Connor. Kennedy has a libertarian streak, and he is skeptical of expansive government power over individuals. In fact, if there's an issue of an individual versus invasive government, Kennedy sides with the individual.
As a result, Kennedy supports the right to possess a firearm for self-defense AND a woman's right in the context of abortion. He opposes certain laws that discriminate against homosexuals or restrict a person's freedom of speech.
Kennedy also is strong on issues of federalism - and is remarkably consistent. His opinion in a 1999 case, Alden v. Maine, is considered one of the Court's finest in that area. Ruling that states were immune from private lawsuits in state courts, Kennedy wrote: "Sovereign immunity derives not from the Eleventh Amendment but from the federal structure of the original Constitution itself."