The Fourth Amendment is the part of the Bill of Rights that prohibits "unreasonable searches and seizures." But — what's unreasonable? That question has fueled a century's worth of court rulings that have dramatically expanded the power of individual police officers in the U.S. Today on the show, how an amendment that was supposed to limit government power has ended up enabling it.

To access bonus episodes and listen to Throughline sponsor-free, subscribe to Throughline+ via Apple Podcasts or at plus.npr.org/throughline.

Of all the amendments to the U.S. Constitution, the 14th is a big one. It's shaped all of our lives, whether we realize it or not: Roe v. Wade, Brown v. Board of Education, Bush v. Gore, plus other Supreme Court cases that legalized same-sex marriage, interracial marriage, access to birth control — they've all been built on the back of the 14th.

The amendment was ratified after the Civil War, and it's packed full of lofty phrases like due process, equal protection, and liberty. But what do those words really guarantee us?

Today on the show: how the 14th Amendment has remade America – and how America has remade the 14th.