REUTERS/Fiscalia General del Estado de Jalisco/Handout via Reuters
U.S. national Ethan Couch is pictured in this undated handout photograph made available to Reuters on December 29, 2015 by the Jalisco state prosecutor office.
Couch appealed Mexico's original decision to deport him, and he has been held in a detention center in the outskirts of Mexico City since then, according to Yahoo! News.
Couch earned the nickname "affluenza teen" after claiming he was so rich and famous that he couldn't tell right from wrong.
After a psychologist used the term in Couch's defense during his trial, a judge sentenced the teen to 10 years drug-and-alcohol-free probation for intoxication manslaughter, which critics say was too lenient.
The term "affluenza" combines affluence and influenza, and its first use traces back to about 1954, when Fred Whitman, a member of one of San Francisco's prominent founding families, used it to describe the supposed psychological and social effects of wealth, including feelings of guilt, lack of motivation, isolation, and extreme materialism rich people suffer from.
The term was later popularized in the late 1990s by the book "The Golden Ghetto" and by a PBS special of the same name. Now, it even appears in the Merriam-Webster Unabridged Dictionary.
Not surprisingly, experts say it's not a real illness.
A made-up illness?
"As a doctor I can assure you that, no, Affluenza is not a real affliction," Michelle London, a Johns Hopkins-trained neuropsychologist and President of the Chicago NeuroRehabilitation Center, wrote in the Daily Beast back in 2013.
"It is a constructed excuse for behavior that gives a privileged teen an out because his father is a millionaire and his defense team is of the Gucci variety," London added.
There is no mention of affluenza in the latest edition of the Diagnostic and Statistical Manual of Mental Disorders, the handbook used by health care professionals. And a search for the term "affluenza" in PubMed Central, a major database of medical research, turned up just four results, only one of which seems to be a serious investigation of the condition. Even that one refers to it as "a metaphorical illness."
"It's a cute idea in the public's imagination, but there's no diagnostic criteria that says people have affluenza," Thomas Plante, a psychologist at Santa Clara University, told Discovery News in 2013.
That said, Plante and other psychologists say that they have noticed this kind of troublesome behavior in rich kids whose parents don't discipline or pay attention to them.
Rich kids, lax parents?
Arizona State University psychologist Suniya Luthar has studied the mattter, and her findings led her to suggest that upper-class kids run a risk of falling into subtance abuse, anxiety and depression because of pressure or isolation from their parents.
"There are families where very, very few limits are set at a time when they should be," Luthar told CNN in 2013. But by the time a child is 16, "The horse is out of the barn," she added.
But as far as psychology is concerned, being rich and having lax parents is not enough to define a mental illness, and definitely isn't an excuse for killing someone.