In cases from North Carolina and Pennsylvania, Republican state legislatures sought to block decisions issued by state supreme courts based on the states' respective constitutions.

The Supreme Court reversed a federal appeals court in Boston that had overturned Dzhokhar Tsarnaev's death sentence. The 2013 attack killed three people.

The outcome of the case could also hamstring the authority of all agencies, from the EPA to the Securities and Exchange Commission to Federal Reserve Board.

In 2017, the court heard a very similar challenge to Colorado's anti-discrimination law from a baker who objected to creating cakes for same-sex weddings.

The Supreme Court set the argument for mid-April, putting an exclamation point on what has already been a blockbuster term. A decision in the case is expected in June.