The US Supreme Court has upheld the law which aims to provide affordable health insurance for all Americans, dismissing a legal challenge from Texas and 17 other Republican-governed states.
This is the third time since 2010 that the Affordable Care Act (ACA), the signature policy of former president Barack Obama, has survived a challenge.
The law gave millions of low-income Americans access to medical insurance.
It bans insurers from denying coverage due to pre-existing conditions.
