The First Amendment guarantees our free exercise of religion. The Religious Freedom Restoration Act forbids the government from “substantially burdening a person’s exercise of religion.”
So what does a substantial burden look like?
If Congress and the Ninth Circuit Court of Appeals fail to protect the sacred religious lands of the Apache at Oak Flat in the Tonto National Forest in Arizona, a foreign mining company will transform this site into a crater 1.8 miles long and as deep as two Washington Monuments. Try holding a worship service, a coming-of-age ceremony, or a gathering of ceremonial and medicinal herbs at the bottom of such a hole surrounded by almost two miles of empty space.
Here are some great tools for visualizing a substantial burden (hat tip to BJC).