Reading Girard, Groundhog Day 2010

From Rene Girard's Violence and the Sacred:

"[T]he judicial process is more concerned with the general security of the community than with any abstract notion of justice."

This may be true. But who defines what serves the general security of the community?

Or, put another way, why was the prison at Guantanamo Bay set up, and why is it still open?