" T he individual mandate is a strange sort of law, so even if the court has established a precedent here that the Commerce Power doesn't authorize Congress to create commerce, that precedent may not have much if any practical significance for other laws," Magarian wrote in an email.

Where's this leave Roberts?

Possibly with one brilliant piece of judicial strategizing.

"If you're imagining a Chief Justice writing this as a judicial politician trying to satisfy constituencies -- you know, give the conservatives something of a bone, don't strike the thing down, write something narrow -- I think you couldn't be much more crafty than this," said Magarian. "Roberts is kind of being a master politician here."

Republican presidential nominee Mitt Romney stopped short on Thursday of disparaging the Supreme Court, saying that the ruling determined Obamacare didn't violate the U.S. Constitution.

Barack Obama played it safe by saying American lives would be more secure because of the high court's decision.

Their comments understate that Thursday's Obamacare ruling is likely the most crucial decision by the Supreme Court since Bush v. Gore in 2000, when then-Chief Justice William Rehnquist wrote the majority opinion. It appears that Roberts just had his Bush v. Gore moment.

Medicaid HMOs soared after the ruling , largely due to an expected 16 to 20 million new Americans who would be eligible to enroll in the government program in 2014: Amerigroup ( AGP) was at $65.47, up $3.07 or 4.9%, Molina ( MOH) at $23.16, up $1.84, or 8.6%, and Centene ( CNC) at $30.59, up 68 cents or 2.3%.

Diversified health care companies fell on the news as the regulatory burdens set by Obamacare -- minimum medical loss ratio, exchanges and rate reviews -- are expected to cause them trouble. Aetna ( AET) closed at $39.85, down $1.11, or 2.7%, Cigna ( CI) was at $44.18, down $1.22, or 2.7%, and Coventry ( CVH) at $32.46, down 77 cents, or 2.3%.

-- Written by Joe Deaux in New York.

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