Ethan Couch was drunk and high when he drove his truck at 70 mph into a group of people, killing four. It was not his fault, though, he was suffering the dread disease "affluenza." Warning: This episode will piss you off.

Sources:

https://www.dmagazine.com/publications/d-magazine/2015/may/affluenza-the-worst-parents-ever-ethan-couch/

https://www.dallasnews.com/news/crime/2015/12/28/reports-mexican-authorities-apprehend-ethan-couch-and-his-mother#_ga=2.4869235.1961014490.1534708349-1377006307.1485230677

https://www.washingtonpost.com/news/morning-mix/wp/2016/01/07/no-such-thing-as-affluenza-not-so-fast/

https://www.psychologytoday.com/us/blog/our-gender-ourselves/201601/is-affluenza-real

http://thescienceexplorer.com/brain-and-body/affluenza-teen-s-psychological-condition-even-real