UNDATED (CNN) -- The online hacking group Anonymous says it is "declaring war" on the U.S. Government after hacking the federal sentencing commission's website overnight.
The group is demanding the U.S. reform its justice system.
Anonymous is believed to be a collective of so-called "hacktivists" who oppose attempts to limit internet freedoms.
A long threat note, YouTube video and a list of files named after U.S. Supreme Court justices were posted on the site taken over by the group.
The note expressed anger over the death of internet activist Aaron Swartz, who committed suicide on January 11th. Swartz was facing criminal charges related to a hacking case when he died.