This report from the National Conference of State Legislatures examines the responses of states to the Affordable Care Act. Some states have taken action to limit the effects of the federal bill, challenging the law in the federal courts or passing state legislation to hinder it.

From the report:

On March 23, 2010, President Obama signed the Patient Protection and Affordable Care Act (PPACA) into law. One week later, he also signed the Health Care and Education Reconciliation Act of 2010, together referred to as the Affordable Care Act, the act, or federal health reform.  

In response to federal health reform, many state legislatures and governors have begun setting up the infrastructure for implementing the new law. State implementation efforts continue to build as provisions take effect and timelines are developed. To date, some of the most common efforts include creating task forces or appointing officials responsible for moving forward with federal requirements and closely examining how to implement major provisions such as health insurance exchanges, insurance reforms, and Medicaid expansion. Legislators in at least 40 states have also proposed legislation to limit, alter or oppose selected state or federal actions, including single-payer provisions and mandates that would require purchase of insurance.

Full Report: State Actions to Implement Federal Health Reform

National Conference of State Legislatures. (2010). State actions to implement federal health reform.