Chief Justice Roberts Is Master Judicial Strategist

NEW YORK (TheStreet) -- As it turns out, the market was dead wrong.

Investors were convinced in late March that Chief Justice John Roberts would strike down Obamacare, while some former Supreme Court clerks warned against such assumptions.

"If you're Roberts, who left himself with wiggle room, who asked hard questions on both sides ... I think Roberts is sensitive to the role of the courts and public opinion about the courts, and those roles are enhanced to the extent the public doesn't think it's a purely partisan decision," Hank Greely, a Stanford University law professor who clerked for former Justice Potter Stewart in the late 1970s, said in a previous interview.

Roberts initially said in the ruling that the individual mandate was not constitutional under the Commerce Clause or the Necessary and Proper Clause -- which faked out some reporters who took the comment to mean the court killed the mandate. He then ultimately surprised many experts when he upheld the mandate based on the "penalty" being a tax.

"The people that I listened to, they leaned towards more of a strike down on this than what was offered," said Allan Flader, senior vice president of investments at RBC Wealth Management.

So why did the reliably conservative Roberts cast the deciding vote?

"Robert's sees himself, as most Chief Justices do, as the guardian of the court's institutional credibility," said Greg Magarian, a law professor at Washington University in St. Louis.

For a Chief Justice sensitive to the court's history, though, it appears that Robert's wrote a rather strange opinion.

Magarian said Robert's opinion was bizarre for a couple reasons. The first is that he took a "two-step" on the tax interpretation. The court held that the suit isn't barred under the anti-injunction act because Congress called the individual mandate payment a penalty rather than a tax. But then the court determined on its own analysis that the payment was a tax.

The second oddity, according to Magarian, is that Roberts even reached the Commerce Clause and Necessary and Proper Clause issues.

Typically, the court prefers to determine a case on the narrowest grounds possible. By that logic, Roberts would have simply upheld the mandate as a tax and finished his judgment there.