The individual insurance requirement that the Supreme Court is reviewing isn't the first federal mandate involving health care.
There's a Medicare payroll tax on workers and employers, for example, and a requirement that hospitals provide free emergency services to indigents. Health care is full of government dictates, some arguably more intrusive than President Barack Obama's overhaul law.
It's a wrinkle that has caught the attention of the justices.
Most of the mandates apply to providers such as hospitals and insurers. For example, a 1990s law requires health plans to cover at least a 48-hour hospital stay for new mothers and their babies. Such requirements protect some consumers while indirectly raising costs for others.
One mandate affects just about everybody: Workers must pay a tax to finance Medicare, which collects about $200 billion a year.
It's right on your W-2 form, line 6, "Medicare tax withheld." Workers must pay it even if they don't have health insurance. Employees of a company get to split the tax with their employer. The self-employed owe the full amount, 2.9 percent of earnings.
Lindsey Donner, a small-business owner from San Diego, pays the Medicare tax although she and her husband are uninsured. Donner, 27, says she doesn't see much difference between the mandate that workers help finance Medicare and the health care law's requirement that nearly everyone has to have some sort of health insurance.
"My understanding of what is going on in the Supreme Court is that it seems to be something of a semantics issue," she said. "Ultimately, I don't see the big difference. If I am paying for Medicare, why can't I also be paying into something that would help me right now or in five years if I want to have children?"