If you read one part of the Supreme Court's ruling upholding President Obama's health care law, make it this breakdown of the Constitution's boundaries for Congress's power. This is the heart of the case:
Although the breadth of Congress’s power to tax is greater than its power to regulate commerce, the taxing power does not give Congress the same degree of control over individual behavior (emphasis added). Once we recognize that Congress may regulate a particular decision under the Commerce Clause, the Federal Government can bring its full weight to bear. Congress may simply command individuals to do as it directs. An individual who disobeys may be subjected to criminal sanctions. Those sanctions can include not only fines and imprisonment, but all the attendant consequences of being branded a criminal: deprivation of otherwise protected civil rights, such as the right to bear arms or vote in elections; loss of employment opportunities; social stigma; and severe disabilities in other controversies, such as custody or immigration disputes.
By contrast, Congress’s authority under the taxing power is limited to requiring an individual to pay money into the Federal Treasury, no more. If a tax is properly paid, the Government has no power to compel or punish individuals subject to it. We do not make light of the severe burden that taxation—especially taxation motivated by a regulatory purpose—can impose. But imposition of a tax nonetheless leaves an individual with a lawful choice to do or not do a certain act, so long as he is willing to pay a tax levied on that choice.
The Affordable Care Act’s requirement that certain individuals pay a financial penalty for not obtaining health insurance may reasonably be characterized as a tax. Because the Constitution permits such a tax, it is not our role to forbid it, or to pass upon its wisdom or fairness.
In politics, taxes matter because they are so unpopular. For the Supreme Court, however, the taxing power is crucial here because it enables Congress to advance a national policy without endangering liberty. You may have to pay for your health care decisions -- that was true before this law passed -- but you will not be punished, sanctioned, deprived or jailed for them.