You ever heard of a "blue law?" It is a former law, that is usually pretty ridiculous, and is not enforced anymore. For example, in Montana, it is illegal for un-married women to go fishing by themselves. It is also illegal for a sheep to ride in the cab of a truck unless 2 humans are in the cab with it. These laws are just silly, but used to be enforced in Montana. But, when it comes to MURDER, that crime is something that is NOT silly and IS enforced everywhere you go.... Except for one little 50 square mile chunk of land.

According to Wikipedia

The Yellowstone Zone of Death is the name given to the 50 sq mi (129.50 km2Idaho section of Yellowstone National Park in which, as a result of a purported loophole in the Constitution of the United States, a criminal could theoretically get away with any crime, up to and including murder

Thats right...MURDER!

You see, Yellowstone was established far before Montana, Wyoming and Idaho became states. After the state boundaries were drawn, Yellowstone stretched into all three states. With about 90% of it residing in the borders of Wyoming. The other 9% is in Montana. And just a smidge of YNP is in the state of Idaho. This little chunk of property is called the death zone because it is in Idaho, but Yellowstone park is considered under the jurisdiction of Wyoming.

According to Bar Room Banter on themeateater.com

Court would need to be held in the state where you committed the crime (Idaho), but also technically in the district where you committed the crime (Wyoming). This creates a tight Venn diagram where you can only be tried within the 50-square-mile section of Yellowstone that’s in Idaho.

So, when it comes to trial by a jury of your peers, you would have to select the jury from a pool of people living in that small 50 square miles. But, there is only one problem. Nobody lives there. Meaning that technically the case would be thrown out, because you couldn't stand a proper trial.

The following video from Vox explains in more detail.