Omer Ninham's attorneys had cited recent U.S. Supreme Court rulings and new science about adolescent brain development to no avail, the Milwaukee Journal Sentinel reported.
Since Ninham was sentenced in 2000 for the 1998 crime, the U.S. Supreme Court has found the death sentence to be cruel and unusual punishment for juveniles, along with life without parole for any crime short of homicide.
Ninham was represented by the Equal Justice Initiative in Alabama, which has two appeals to the U.S. Supreme Court, but they involve juveniles who had lesser roles in their crimes.
Ninham and four other minors attacked Zong Vang, a stranger to them, while he was riding his bike in Green Bay. Richard Crapeau, 13, threw Vang off his bike, and Ninham punched him.
The group chased Vang up to the roof of a five-story parking garage. Ninham and Crapeau grabbed the victim, swung him over the edge and dropped him as their friends egged them on, court records say.
Crapeau was also sentenced to life, but with the chance of parole after 50 years.