Graham was consistent with a general trend exhibited by the court to create a more clear differentiation between appropriate juvenile vs. adult sentencing. For example, in Roper v. Simmons (2005) the court declared the death penalty unconstitutional for persons under 18 (Guggenheim 2012: 3). However, the Graham decision was considered more surprising because the Court tends to give more consideration to death penalty cases. There is often great variation between juvenile laws between the states, but rather than defer to a growing trend to emphasize states' rights, the Graham decision emphasized evolving national and international standards of decency. According to Justice Kennedy, regardless of the state in which the juvenile is tried, there must be a general acknowledgement that juveniles have a "lack of maturity...

"Graham is the first case ever to side with minors in their claim that they have a right to be treated as children even when the state does not agree" and that certain types of penalties (not only the death penalty) are cruel and unusual specifically when they are used against children (Guggenheim 2012:35).
References

Graham v. Florida. (2010). Cornell Law School. Retrieved:

http://www.law.cornell.edu/supct/html/08-7412.ZS.html

Guggenheim, M. (2012.).Graham v. Florida and a juvenile's right to age-appropriate sentencing

Harvard CRCL. Retrieved:

http://harvardcrcl.org/wp-content/uploads/2012/03/Guggenheim-Graham-v.-Florida.pdf