WASHINGTON -- Television cameras will surround the Supreme Court Thursday morning, as they did Monday, anticipating something that may, again, not happen.

The momentous healthcare decision could be announced Thursday. Or not. All we really know is that it is extremely likely to be handed down by the following Thursday, June 28, when the court is expected to end its current term.

The court works in secrecy as it prepares its opinions, and outsiders might be surprised to learn that some of its work is done at the last minute. The justices would have voted almost immediately after three days of oral arguments last March on whether President Obama’s healthcare overhaul is constitutional. Although that vote would normally have determined the outcome of the case, there is a lot of back and forth before the majority opinion and the dissents, if any, are finished.

Last Friday was the deadline for justices to hand in dissents. Then whoever is writing the majority opinion – the betting is on Chief Justice John G. Roberts Jr. – has the option of responding to any criticism of the ruling in his own opinion.

The decisions are printed inside the ornate 1935 Corinthian-style building, and handed out to reporters as the justice who authored the opinion announces the decision from the bench shortly after 10 a.m. By tradition the senior justice goes last, so healthcare is likely to be the last decision announced on the day it comes down.

Only a few times in modern history have the results leaked ahead of time, once reputedly from a comment by a justice to a reporter, another time from a talkative printer.

The court is not meeting Friday, so if the healthcare decision does not come Thursday, the next opportunity would be Monday.

Next week the tension will intensify. If the healthcare decision is not announced before the 28th, that day is likely to be wild: It would be the first time reporters and the public would go to court knowing they would witness what could be one of the most significant constitutional rulings of the century.

tim.phelps@latimes.com