The issue focused on whether states had the legal authority to ban guns that can be bought without a background check.

The Post said that if the bill became law, "the majority of states would have to stop selling guns to people who do not have a background check."

In other words, if the bill became law, any gun sales from people who do not have a background check would be illegal.

It's not clear how many gun sales would be affected. The Post also reported that "