A week ago, supporters of the Affordable Care Act and legal scholars seemed certain that the Supreme Court would find the law constitutional, by a 6-3 or even a 7-2 vote. But after three days of contentious hearings this week, such forecasts seem presumptuous: The five members of the court's conservative majority all apparently doubt whether Congress has the authority to force (nearly) every American to buy health insurance (the "individual mandate"), an essential provision of President Obama's health-care overhaul. How did so many people get their predictions so wrong? Here, four theories:

1. Obama's lawyer unexpectedly blew it
Solicitor General Donald Verrilli's defense of ObamaCare "may go down as one of the most spectacular flameouts in the history of the court," says Adam Serwer at Mother Jones. He was fighting for "liberalism's biggest domestic accomplishment since the 1960s," but came across like a stammering teenager, stumbling over the "most predictable of questions." Verrilli parroted tired talking points instead of clearly explaining how enforcing the individual mandate wouldn't give the government unlimited powers. "If the law is upheld, it will be in spite of Verrilli's performance, not because of it."

2. Nobody knew Scalia would embrace Tea Party talking points
ObamaCare's proponents "were badly caught off guard by the depth of the conservative bloc's apparent hostility toward the law," says Greg Sargent at The Washington Post, "and its willingness to embrace the hard right's arguments against its constitutionality." Justice Antonin Scalia, whom Obama administration officials had viewed as a potential swing vote, even invoked the "broccoli argument," asking whether, if Congress can order people to buy health insurance, it can't force them to eat broccoli, too. That "language is straight out of the Tea Party guerrilla manual that was written during the battle to prevent ObamaCare from becoming law in the first place."

3. The reform law's backers were delusional
The only surprising thing here, says John Hinderaker at Power Line, is that our nanny state might finally be "back on the path to constitutional government." The bottom line is that the Commerce Clause, which supporters say gives Congress the power to impose the insurance mandate, is way more limited in scope than fans of Obama's health-care power grab claim. Assuming the law would pass constitutional muster was pure hubris.

4. They were just wrong... or were they?
This wouldn't be the first time Supreme Court predictions missed the mark, says Thomas M. Keck at Britain's Guardian. Remember Bush v. Gore in 2000? Most legal scholars were certain the Supreme Court would decline to intervene, since precedents suggested that Electoral College disputes should be resolved by state authorities or Congress. Wrong! And if the court strikes down ObamaCare, it will do so again by a 5-4 conservative majority. Of course, there's another possibility: Maybe Chief Justice John Roberts or swing vote Justice Anthony Kennedy will vote to uphold ObamaCare, if only out of fear that striking it down "will be remembered for 100 years as the product of a partisan and undemocratic court."