As the Patient Protection and Affordable Care Act marks a big milestone (it turned 5 on March 23), we look back on the law's biggest moments, movers and motives.

1. Supreme Court case on the law's constitutionality (March 2012)

The Patient Protection and Affordable Care Act didn't have to wait long for a big, big moment: Just two years after being signed into law, it went to the Supreme Court in a big way. The court announced it would hear a case about the law's constitutionality after 26 states—led by Florida—sued the government over the law's linchpin, the individual mandate, arguing individuals couldn't be forced to buy insurance. The court heard three days of politically charged arguments March 26–28 over the constitutionality of PPACA. It was a case that divided the nation.