He upholds the individual mandate—as a tax, not a penalty—as the law of the land. But then says it would not be "unlawful" for Americans to violate the law's mandate that they "shall" buy health insurance--as long as they are willing to pay the "penalty" for not obeying the law.

Roberts first examines the question of whether the Anti-Injunction Act prohibits Americans from bringing suit against Obamacare at this time.

“The Anti-Injunction Act provides that ‘no suit for the purpose of restraining the assessment or collection of any tax shall be maintained in any court by any person, whether or not such person is the person against whom such tax was assessed,’” Roberts explains.

“Amicus contends that the Internal Revenue Code treats the penalty as a tax, and that the Anti-Injunction Act therefore bars this suit,” says Roberts.

Roberts thus concludes that because Congress calls the penalty for not complying with the individual mandate a “penalty” not a “tax,” the "penalty" therefore is not a "tax."

“The Affordable Care Act does not require that the penalty for failing to comply with the individual mandate be treated as a tax for purposes of the Anti-injunction Act,” writes Roberts. “The Anti-Injunction Act therefore does not apply to this suit, and we may proceed to the merits.”

Got it? The chief justice of the United States says the penalty for not obeying the individual mandate is not a tax, it's a penalty. Therefore, the court can rule on it at this time.

Remember: Roberts says, It's not a tax, it's a penalty.

“It is of course true that the Act describes the payment as a ‘penalty,’ not a ‘tax,” says Roberts. “But while that label is fatal to the application of the Anti-Injunction Act, it does not determine whether the payment may be viewed as an exercise of Congress’s taxing power.”

Roberts then concludes that he while he considered the "penalty' and "penalty" in determining that his court could take up Obamcare and rule on it, he will now consider the “penalty” a “tax” for purposes of allowing Congress to force people to buy health insurance.