WASHINGTON - President Barack Obama's landmark health care reforms take effect on Wednesday, granting coverage to millions of previously uninsured Americans after nearly four years of bitter wrangling that has loomed large over the US political landscape.
Since the Affordable Care Act, or "Obamacare", was passed in 2010, the legislation has survived multiple repeal attempts by Republican lawmakers, a US Supreme Court hearing, and a disastrous rollout of the website set up to assist the launch of the legislation.
But as of January 1, 2014, it will be illegal for insurers to deny coverage because of pre-existing conditions or to limit the level of annual reimbursements for essential services - practices in the past which had left some patients facing financial ruin.
Under the Affordable Care Act, it will now be mandatory for any US resident to enroll in a health care plan.
Failure to do so will be punishable by a $95 fine, a figure that will rise to $695 (S$877) in 2014.
The economic reasoning of the legislation is that if everyone contributes to the system the premiums paid by healthy people should offset the additional costs associated with the US citizens who are the most costly to insure.
In a significant first, the new legislation defines treatments that insurers must cover. All insurance must now include cover for hospitalizations, including emergencies.
And preventative care - such as screenings for diabetes or cancer, vaccines or contraception - should also be fully reimbursed.
"The new law is transformational for our entire health care system," Health Secretary Kathleen Sebelius said Tuesday.
For the estimated 150 million Americans who are insured through their employers in the United States, where only the poorest and those over 65 are insured through Social Security, there will be little or no change.