The U.S. Supreme Court has upheld the Affordable Care Act, also known as “Obamacare,” the health insurance overhaul that President Barack Obama signed into law in March 2010. The law requires virtually all Americans to have health insurance by 2014.

The ruling allows the law to continue on its dual mission: to extend health insurance to many of the estimated 50 million Americans who are currently uninsured; and to tame runaway health care costs.

It will proceed toward new changes for American health care, including the introduction in 2014 of the so-called individual mandate, which will require uninsured Americans to buy health insurance or face tax penalties.

In Thursday’s decision, the court says Congress had the ability to impose the mandate under its taxing power.

The mandate was a focal point of the legal challenge that reached the Supreme Court. In a lawsuit, opponents including 26 states and the National Federation of Independent Business claimed that the requirement to purchase insurance goes against the U.S. Constitution.

The idea behind the mandate is that with more people insured, rates can be kept affordable even as insurers comply with other parts of the law, such as its ban on charging people with pre-existing conditions more for insurance or even denying them coverage altogether. That provision also takes effect in 2014.

Several of the nation’s largest health insurers had said that regardless of the way the court ruled, they didn’t plan to undo provisions of the law which are already in effect and have proved to be popular. For example, UnitedHealthcare, Humana and Aetna announced earlier this month that they would continue to allow adult children up to age 26 to be covered under their parents’ health insurance. The insurance giants also said they would keep providing shots, screenings and other preventive care to health plan members free of charge, with no copayment required.

The law also requires states to set up health exchanges, marketplaces for consumers to go to compare prices and buy insurance, also starting in 2014. Some states were been waiting to see what the Supreme Court would do before taking steps toward setting up their exchange.

Congressional Republicans have said they will keep pushing for a full repeal of the law.

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