Two other federal judges - in Detroit and Lynchburg, Va. - have upheld the insurance mandate.
The bill also included an insurance mandate for every American.
The strengths and weaknesses of a federal judge's decision rejecting the insurance mandate.
The insurance mandate is central to the law's mission of covering more than 30 million people who are uninsured.
The insurance mandate does not take effect until 2014.
Q: How will the insurance mandate be enforced?
Q. What are some of the potential pitfalls of the insurance mandate at the federal level?
The proposal for an "insurance mandate" and subsidies would increase federal spending on vaccines, by an unspecified amount, and is subject to approval by Congress.
The insurance mandate is going to require healthy people to buy health insurance, so in the individual market, it's going to be a lot cheaper.
Twenty-six state attorneys general filed a lawsuit against the federal government claiming the insurance mandate is unconstitutional.